Hope, I'm glad you had this discussion w/your h. It will help you to better understand everything that was involved w/him trying to find himself. He's hitting bottom and that's good. He's also reaching out as I suspected he would to you. You did an excellent job of listening and hopefully some of what you told him will sink in. Give him plenty of space and be there as a friend to listen. He's very fragile right now.
As for the fil, he can't help him. Your fil knew that the journey your h was on was one of self. Yes, he could have been there to listen, but the bottom line was that your h needed to do this on his own for he wouldn't have listened to his father or anyone else while traveling in the time zone of hell.
I hope that you are planning some wonderful hobbies for the fall and are keeping yourself busy. Hope, you are an amazing lady who has traveled the hard road with a lot of pot holes in it. You are going to be okay. Your h will be okay in time as well. He just needs to finish us his self discovery.
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.