UCLAFan,

You're an adult, you don't have to answer to anyone but yourself. Like Perna said (and you are my hero Perna, always spot on advice) make your own plans, and if someone invites you, "I'm sorry I've got other plans."

You don't owe your mother anything. I suspect you hope each time you see her that this will be the time she learns to appreciate you and enjoy your company. If she hasn't yet, I don't think there's much hope for that. You sound like a kind and gentle soul, and some people just don't appreciate that.

Life is too short to try to please other people. You have to make decisions that are right, healthy and enjoyable for yourself. Surround yourself with people that are good and kind and leave the jerks behind whether they happen to be related or not. Look out for yourself, you're the only one that will.