You seem to be weilding the Darkness tecnique lika a weapon. It seems to have accomplished what it was supposed to. What more are you hoping to accomplish by staying dard?
What now? So you enforce your boundaries. He stays sober, He operates with 100% transparency. He gets rid of the pictures of the other chick and whatever other reminders, you let him know you will not compromise and if he agrees (and actually does it), you can slowly move forward.
It sounds like you pretty much have the power at this point but are too scared to exercise it. He is making noise like he wants to put it back together. So you have to do the work, which in this instance means being brave enough to not allow that crap. Set the boudaries. The ONLY way EVER you will feel safe and trusting enough is to lay down the ground rules/boundaries. Yeah! he may not put up with it. Then out he goes. OR he will and you will then be able to start to trust and maybe move past roommate status.
I know I am sounding like a broken record but as an unemotional third party observer, your current situation seems really positive, and fairly clear cut, if you have the strength to stand your ground and call the shots.
Please list your ground rules/boundaries.
Me 44 She 46 S13 D9 M18 T23 3 years DB'ing Successfully busted
