My mother and I had a very rough relationship while I was growing up. In my twenties I started to distance myself from her. I realized, with the help of a therapist, that she wasn't necessarily going to change and that I couldn't make her. I could only change my actions around her. More and more I stood up to her. I stayed away when she "misbehaved". Our relationship became better when I had children. I had my boundaries set. I think that is very hard to do because no matter how old you are you get caught up in past behaviors and responses. I had to make sure I didn't respond in my old ways.
I have compassion for your mom for what she went through. This doesn't mean I think what she is doing to you is acceptable. I know my mom comes from a different generation that believes they deal with things(by not really dealing with them) and that everything is "fine". I could tell by her behavior that she didn't really deal with things and everything was not fine. Unfortunately she did not see this. Something I had to accept because you can't make people see things you don't.
As far as bringing you around that Uncle, I know that is hard to understand. When I asked a therapist why my mom picked out and abusive sitter for us, she said she went with what she knew. Not that she intentionally said hey that person is abusive I'll hire her, but that she felt some sort of comfort with her. Sad, but I get it.
Now, for raising my children...I try not to repeat patterns. My kids didn't grow up wondering if they were loved. I am not perfect and the times that have been questionable, we have talked about ever since they were little guys. Mommy, me, admitted when she wasn't well behaved, when she flew off the handle. It didn't happen often, but it happened. The thing is I never led my children to believe my behavior was their fault.
Your mother, as my mother, could have made a choice to be better but they stuck with what they knew. They locked themselves in. You can still have a relationship with your mother but it has to be on your terms. That is going to cause a lot of upheavals. I know it did with my mom. My children had a relationship with my mom because I didn't want my relationship with her to be theirs. Does that make any sense? My burdens or pains were not going to be theirs. I guess, I didn't have the same relationship with my grandma that my mom did. I look at it that way. Not to say I wasn't hyper-vigilant in making sure they were treated well. Same with my dad. They get to choose their relationships, but I am and have been their protector. Thankfully they've seen that.
In the end you have to decide what it is worth to you to maintain a relationship with her. Boundaries are important. Getting her to treat you like an adult is going to be difficult. Not feeling like the child you once were is going to be difficult. I know, I've been there. I decided to keep my relationship with my mom, but it was on my terms. Sounds harsh, doesn't it?
My mom died two years ago and I miss her tremendously. I never thought I would be able to say that, but her death caused me grief beyond belief.