Saddest death:
I'm basically going to list everyone's death scenes but that's okay.
Peter's 'I don't feel so good': It was so sad because everyone around him was disappearing and his body was trying to fight it, so he went for the one person who gave him comfort, Tony.
Natasha's 'It's okay': It was so sad because she was looking into her best friend's eyes and telling him it was okay, and to let her die. It just hit so hard!
Fitz's 'I think my legs are broken': Even when Fitz was dying, he was still making jokes and was still worried about other people. And the way Mack and May treated him dying, reassuring him that it was okay, and that they were going to be okay, was just so sad.