I am sorry you’ve had to deal with the abuse and now with a selfish mother. Leaving was what you needed to do for self-care. I’d invest my time and energy into building a life you can enjoy. A mother who treats you so poorly, feels she is entitled to enslave you, and then try to make you feel guilty for growing up doesn’t have much to offer. You are 26 and need to build a life of your own. Let her hold a grudge, or be angry, or whatever else she wants to do. My guess is that as time goes on you’ll find a way to reconnect with your special needs brother. But until then I would enter into some type of counseling to grieve leaving your family as you build a life for yourself.