I'm so glad to hear you are in therapy ((((((((( myoasis )))))))))))).
Have you talked with your T about approaching your mom about your feelings and thoughts? If so, what did your T suggest?
Sometimes when we are working through relationships and problems stemming from them, we have this huge need to make the other person know how they made us feel. Sometimes we are strong enough to do that and hold our own, being prepared for what may be dished out to us, and other times, we really are not strong enough.
About 9 months ago, my husband decided he wanted to end our marriage. I received very little feedback from him as to why. He never spoke to me of any issues he was having...there was a complete lack of communication on his part and I was left wondering what the heck happened here??? There was such hurt and betrayal that I felt and I really wanted to communicate all that to him and in a way, I wanted him to hurt the same way he had hurt me. But I fought telling him. It was hard to fight. But I knew I was still feeling too vulnerable to discuss it with him and I didn't think I could hold my own and walk away feeling better for having had my say. I waited to work through the initial feelings...and I'm really glad I did. In time I was able to work through my pain and speak rationally to him about how he made me feel, how he had hurt me. I expected him to be cold and unfeeling and for the most part he was. It didn't bother me as much as it could have had I decided to confront him before I did some self healing.
So, that is why I suggest to you to find some healing and prepare yourself for every possible reaction you could receive when you confront her. Good self care

sabby