My mom makes sure that the conveys just how much she hates me every chance she gets, but she dotes on my sisters. What's your advice?

My sisters get text messages from her telling them how much she misses them. Me? I get comments like “I wish you were never born.”

This is why I am suggesting you see as little of your mother and younger sister as possible. If you must see them, spend as little time alone with either of them as possible. Start developing relationships with people who are caring and supportive.