Never feel guilty for something that you love doing (unless it's illegal).
Believe it or not, your mom loves you, she just has a weird way of showing it.
She may just be really stressed out and is not realizing that she's taking it out on you, or she may not know how to necessarily cope with having a child with a disability because everyone wants the best for their children, and when they're faced with their child having a disability they can sometimes take out their anger on their loved ones, including themselves.
Me being the black sheep of the family, I can tell you that molding yourself into what you think she wants is not the answer. You are you, and you should celebrate that rather than beat yourself up for it.
When your mom says awful things like how she wish she would have put you somewhere so she could have raised your little brother...don't give her the reaction she wants. While hearing something like that may hurt to the high heavens, reply back with something positive and take charge of the situation.
Try to find activities that you and your mom can do together, to remind her that you are still her daughter and that your disability does not define who you are.
And if things still are rocky (and you are of age), maybe look into ways you can move out. If you're in the United States, some states help people with disabilities live on their own. That would give you the space you need to grow and be happy, and your mom will hopefully finally realize how lucky she is to have you.
Never forget that you are an amazing person and your disability shows how strong you are. People think of disabilities as a person having a handicap in life; while that may be true, you may have to take that extra step compared to other people, which shows how much stronger and more willpower you have than most.