Shelli, you don't have to stay just because he went to treatment. Any time you've had enough, you are totally within your rights to walk away. Not because of him, or what he did, but because you don't want to be in the relationship anymore.
I know your whole dilemma with the apartment and all, but it's really up to you whether having the apartment is worth being in a relationship you don't want. From the way you were talking for the past few weeks, all you wanted was to get him OUT of there.
It's your life, and your choices, but it doesn't seem to me that you want HIM particularly, any more.