Do you WANT to take him back? You don't owe it to him, remember.
If you think you might want to take him back, I strongly suggest couples counseling first, as well as individual counseling for yourself. If he's been seeing a psychologist and going to AA meetings, he should continue doing that. Don't have sex, don't let him move back in yet ... just go to counseling together and decide if it might be worth giving him another chance (and if you do, take it SLOW).
If you would rather not risk getting hurt again, just tell him NO, it's over, and that's that. If he's living in his car then that's his problem, not yours. He's responsible for himself, not you.