I doubt he even knows why he does the stuff he does. His addiction is in the driver's seat. He is physically and mentally sick, and you will make yourself sick trying to get in his head. You're more worried about him than he is about himself.
If you want to get off this merry go round and heal yourself, then keep doing good healthy things- Alanon, SR, reading, good self care. Make a list of all the bad stuff and refer to it when you start feeling nostalgic for the "good parts." Maintain the no contact, even when he returns. Can you give his stuff to someone else to give back to him? You deserve better than this.