I'm very sorry about your son, but at least his father and older brother have him under their wings now. He was a lost soul, confused and probably acting out because of how he's been feeling w/the situation. True, typical teenage behavior, but then again you do have to wonder if some of his behavior wasn't trigged by what his father has done. I'm hoping and praying that being w/his father and older brother will help him to bond w/the males in his life and he can get his act together. I do think you did the right thing in ringing up his father about the situation.
As for your h, he's trying to be honest w/you about what is going on w/him. You'll need to detach a bit more and continue to treat him as you would a friend. If you become emotionally involved w/him during this time, his roller coaster will drag you down to the bottom w/him. You can be there to listen and support him, but keep your expectations at zero. It sounds like he's starting to question himself, his life and what he has done and continues to do. This is a good step in the right direction...but he's still go a ways to go and no one knows what he will decide to do.
Please be careful...try to remember that you didn't break him, therefore, you can't fix him. He's got to do that all on his own. Keep your expectations at zero and continue moving forward. If he wants to be a part of your life again, he will find a way to catch up, earn your trust and respect once again.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
