If you were manipulated out of signing the deed for a home you paid for, it seems to me that it would be helpful to see a lawyer who specializes in disability law. You are essentially being held hostage in your own home. It’s your house. She doesn’t get to set house rules for a 26-year-old man who is letting her share his home. She doesn’t get to decide whether you can drive a car you paid for. Being disabled doesn’t mean that you don’t have the same rights as any other adult.
Taking all you said at face value: It looks to me that your mother is, in fact, the dependent one. If you assert your rights to your home, where is she going to go? One way to keep her home is to make sure you don’t meet someone to marry. If you go places without her, you just might meet someone to love. She would then have competition for your affection and for your loyalty.
At this point, the problem isn’t your mother. It’s that you have given her far too much power. Her threats and rules only mean something if you go along with them. You’ve been so beaten down that you have lost the ability to stand up for yourself. If that’s the case, find a lawyer. Then find a therapist to help you learn how to assert some boundaries with your mother.
On the other hand: I don’t have enough information to know if just maybe your mother’s worries are warranted. You didn’t share whether you have done things that make her behavior make a kind of sense. What looks like control could be protection. If you’ve behaved in such a way that she is justified in thinking you aren’t capable of managing a house or driving responsibly, that changes everything. In that case, my best suggestion is that you go together to a family therapist to help the two of you figure out what you need to do so that she feels comfortable with letting go.
I wish you well.