Yes it was about Walt coming to terms with what he had done at the end of his life.
As I said in my previous post though, I don't see that his final moments in the Meth lab point to anything in terms of trying to help Jessie, which was the point you were previously making.
He of course 'saved' Jessie by wrestling him to the floor when he started the M60, but that could also just be seen as a valid excuse for getting himself to the floor in order to set it off.
It's also apparent that Walt thought Jessie was working with Jack's gang and would have fully intended to kill him if involved, he didn't know he was a slave. At the end there, Walt clearly expected Jessie to kill him because of his rage and the fact he typically did what Walt told him to do.
Lydia had to go because she was a major player in the supply chain and also threatened his family. There is also the fact that she knew Skyler had some involvement, so if it came to trial, it could implicate her. The justification for her death was fully there in her final phone call where she had clearly ordered the gang to take Walt's life.
