Pax's suicide in the fourth episode, and Conner's ensuing breakdown. It's mirrored by his second breakdown in the flash-forward after the murder.
Annalise breaking down while she explains to Wes that she and her husband have been trying and failing to have a child, and it's been putting a lot of stress on her—and it's even worse because it really seems like she's telling all of this to a new student because she doesn't have any friends or anyone she could talk to about it. It gets even worse when she reveals in episode seven that she had several miscarriages.
After episode 9, this gets a much darker turn...
Asher calling out his father, practically begging him to say that he wasn't involved in getting an innocent man sentenced to death. It ends with his father calling him ungrateful and throwing him out. And yet even then, Asher still demands that Annalise keep his father out of the proceedings.
Bonnie's complete breakdown in "He Has A Wife" is upsetting, especially when compared to her usual behavior.
Asher having a party for the other Keating Four, but nobody showing up, except for Michaela... but she's just there to steal the trophy.
Sam and Annalise's fight on the night of the murder. A lot of really cruel things are said, like Annalise rubbing her affair in his face and Sam calling her a coward, monster and slut. After Sam comes close to strangling her in a fit of rage, Annalise storms out and returns home hours later to leave him a heartfelt voice message that he's never going to hear because he's dead. Twenty years of marriage, over just like that.
It kinda gets worse when it's revealed the message is just a full-blown lie, in order to throw suspicion off of her.
Whether you like her or not, Aiden breaking up with Michaela was pretty rough.
Annalise's anger at her mother for knowing about the sexual abuse she suffered at the hands of her Uncle Clyde.
Three words from Oliver: "I tested positive."
Rebecca's reaction to finding Lila's corpse in the flashback. After everything that happened, it's clear that she really did care about Lila.
And her heartbroken face when Lila admits that she was never really her friend. Lila blames Rebecca for everything bad that happened to her, says she was just using her as a distraction from her troubled life, and calls her a "trashed-out druggie whore".
Not only that, from what we can see Rebecca truly cared for both Wes and Lila, and trusted them enough to drop her defenses around them. Only for Lila to call her worthless and leave her. As well as Wes who loses faith in her and starts believing that she murdered the only other person she cared about. In the end Wes finally believes in her again and steps up to defend her, but by that time it's most likely the Rebecca is already dead and will never know that the man she loved stood up for her.
Eve (the lawyer Annalise told Nate to call) calling out Annalise for her constant manipulations of others and saying there's nothing good in her.
Annalise crying in the bathroom after her brutal cross on the stand.
The next morning after a night of passion, Eve heads off to New York and asks Annalise to come with her. Going by the flashforwards with Annalise on the brink of death, that might never happen.
Bonnie and Asher bringing an end to their relationship.
Annalise on the verge of dying as paramedics attempt to revive her heartbeat is a very disconcerting one, as it appears that the Keating Four and Nate have abandoned her.
Michaela's breakdown after she finds out that Levi is actually "Eggs 911" and has been using her.
Bonnie's backstory: Her father sexually abused her and put it all online. This drives Asher to tears.
Asher becoming greatly (and justly) upset at his father for only thinking of himself when he's about to sign an immunity agreement. Their relationship has only gotten worse.
Bonnie saying, "I love you," to try to stop Asher going to police.
Bonnie sobbing in her car as she speaks to Annalise about Asher going to the police. She's so distraught over letting Annalise down.
Caleb overhears a recording of his aunt making malicious, racist comments about him and Catherine, saying that their parents shouldn't have adopted them, and realizes that she never truly thought of them as family.
Bonnie discovers that Annalise told Asher about her past history of sexual abuse by her father. She angrily tells Annalise that she's ruined the only good thing in her life, and that she wants Annalise to die.
Bonnie's Shower of Angst in the beginning of the episode, ignoring Annalise's phone calls while the latter is actually checking on her and wanting to apologize for what she did.
Connor's breakdown over Oliver's disappearance while everyone else but Annalise is being dismissive about it. In fact, Annalise, although begrudgingly, has Nate initiate a missing person search while reassuring Connor that everything will be fine.
Asher's father killing himself to avoid the investigation into it. The way Asher has kind of shut down from it and the fact that his mother practically disowns him out of blaming him for it. The Freak Out he has in his car after all this is an entirely believeable one.
This moment isn't exactly helped by the fact that, when Michaela makes a plan to call him to check on him, they all discover that none of them actually have his number. This obviously means that none of them talk to him outside of work or class and probably actively ignore him in their day-to-day lives.
The way the Keating Five end the episode, all various flavors of broken and shocked.
Wes going into a spiral after shooting Annalise, emotionally and mentally wrecked, culminating in him breaking into her house (to search for information she might have on his mother) and finding her pain meds. While he doesn't take the pills, he still says he finally understands why his mother committed suicide: because she wanted the pain to stop.
Annalise spends half the episode hallucinating a baby boy while doped up on her meds. Then comes the flashback to her first meeting Wes and his mother, and she's heavily pregnant. It's obvious something happened to that baby. Even worse, Bonnie implies it isn't the first time Annalise has hallucinated that child before.
Laurel breaking into tears when she can't get a hold of Wes, and wonders out loud if Asher would have killed Sinclair if any of them had taken the time to check on him.
The defendant has a My God, What Have I Done? moment and tearfully confesses to the victim's mother that the killing was intentional. What makes it worse? To cover up the crime, he texted "I luv you" to her so she'd think her son was still alive. Even Michaela sheds a tear upon hearing this.
The fact that the above doesn't deter the woman from her firm belief that the defendant should be released, and even promises him she'll keep in touch with him as they take him away.
The flashback to the day Annalise lost her baby. She got into a car accident and had an emergency Caesarean, but the baby had already died. It's hard to watch Annalise break down, wailing over her baby son's body and apologizing to a distraught Sam, blaming herself for their child's death.
This is intercut with Annalise tearfully confessing to Wes the circumstances of his mother's death.
"His name was Sam."
Connor and Oliver breaking up, due to Ollie finally realizing that their experiences with Annalise have turned them into different, destructive people.
Bonnie tracks down Frank and they entertain the thought of running away from all their problems only for Frank to disappear soon after, leaving Bonnie devastated.
Annalise gets into a terrible drinking spiral and spends the day curled in bed remembering her relationship with Sam before everything went wrong.
After reconciling briefly, Connor and Oliver break up yet again, after a huge fight where Oliver accidentally reveals that he thinks Connor is emotionally damaged. Connor is so upset that he kicks Mikaela's table in two while fighting off tears.
Frank's harrowing confrontation with Annalise. After being rejected by both Bonnie and Laurel, he just sits there and cries while Annalise finally gets to unload on him for his part in the death of her unborn son. The episode ends with Frank getting ready to kill himself, with Annalise screaming for him to do it and Bonnie tearfully begging him to stop.
Fortunately, it's revealed in the following episode that he didn't go through with it.
We learn who is under the sheet: It's Wes. And everyone is visibly floored and freaking out about it: All of the Keating Five (now Four) break down into tears, Annalise is inconsolably shrieking the word "No!", Bonnie is reluctant to say a word to anyone about it, and even former police officer Nate is visibly disturbed by the sight of Wes' burned body.
The fact that Laurel is pregnant with (presumably) his child, and now has to live with the fact that the last time she spoke to Wes, they got into a fight.
Wes's memorial service, where Laurel has to speak and is visibly shaken by it, sounding on the verge of tears through most of it until she straight up breaks down on the podium.
Laurel is just a tearjerking machine throughout the entire episode basically.
Annalise's mother is suffering from severe dementia, to the point of mistaking the housefire Annalise was arrested for as being the one she committed to kill the man molesting her.
The full story of how Wes died. Alone, drugged, and begging for help. Choked to death on a rag and then burnt like trash, with Annalise trying to paint him as a violent sociopathic murderer Driven to Suicide out of guilt. He's basically doomed to be remembered as a criminal, not the good guy that his friends knew him to be.
Annalise finally opening up at AA, acknowledging all the wrong she has done and the guilt she feels for everything, especially Wes.
Annalise firing everyone, after she concludes that they're all better off without her.
Just as Annalise predicted in the previous episode, Jasmine's revealed to have died, likely from a drug overdose.
Bonnie's backstory, which is even more horrifying than previously thought, as well as her breakdown in her therapist's office, where she says that she loves Annalise repeatedly.
Annalise's devastation after Bonnie undermines her class action lawsuit before it can get off the ground - The sheer joy on her face right before the first call, one of the first genuine and pure smiles we get to see from her emphasizes just how bad this hurt her.