You are definitely in unchartered territory and each and every time you have contact w/him, something new will be revealed. He feels comfortable talking to you...so listen closely and you will learn quite a bit about the man he is today.
I don't think he's having such a great time w/all of those new friends of his. If he's taken up weight lifting, he's filling a void not only left by you, but he's got a lot of time on his hands.
BTW, they do tend to be moody at times...just roll w/the punches and don't take it personally.
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.
