Ugh, how hard. I'm so sorry.
I would trust your instincts that are telling you he's becoming more self-centered in treatment...while it's absolutely true that he needs to focus on his recovery, that's different than just focusing on himself.
Maybe it's just too early for him to be counseled to look at how his behavior has affected others...but keep listening to your gut.
Also...yes, I'm a terrible cynic, but he wouldn't be the first person in rehab to exaggerate or fabricate what the therapists are telling him in order to make himself look more like a victim.
Take care of you. If you only have the energy to go once a week or don't want to go at all, given your valid ambivalence about the relationship, that's your prerogative.
Sending you a hug.