Sounds like a real pickle. I feel for you. It's hard to deal with having to live with an ex. I suggest trying to focus on yourself and your life. Try to get a job and stay away from your ex as much as possible. That way the temptation to let him pull you in is less likely. Be busy and that way you can't have time for him. After all if you have been out running & come home have a shower and go to bed in the evening, you're less likely to see him and stay to chat. Similar morning scenario, get up early and get out to the library or other places and come back when you know he'll have left for work.
If he wants to have a proper chat, reconcile, then he can let you know. Good luck.
All the best,