In Episode 1, Sacha says that Tom "puts on a good act" referring to his eulogy. It then turns out Tom was behind the murder of Kate and their children. The sadness comes in when you remember the ending, where Tom is beside himself with regret due to surviving when he intended to die as well. His sadness at the funeral wasn't an act. But not even Sacha who appears to know him better, believes it. Just because he "did it".
