I think it's a bit too soon for him to be moving back in. He needed to be living on his own and not at his sister's house. The man has to grow up before he can heal and become the man he should be. You may not get a true apology from him for a very long time. He may feel pressured to move back home because of the financials, etc.

I would suggest that you dig deeper for patience and do not be surprised if he leaves again. I'm sorry if I sound like a downer on this one, but he doesn't appear to be ready to do any of the heavy lifting to get his life back on track and work on a reconciliation.

I hope that I am wrong and If I am, I will be the first to apologize to you.

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.