It is up to you to decide how much, if any, relationship you have with anyone. The relationship with the roommate sounds very intrusive and dependent, and not what you want. I think it would take a lot of very hard and continuous work to remain roommates when you each want something very different. That is the way with co-dependency relationships.

The roommate even intruded on your therapy. When you no longer have the enmeshed relationships going on, I think you will feel better and your therapy will feel better too.