No, you're not being selfish. What you are trying to do is self-preservation....big difference.
I'm sorry that your mom is not getting it. My stepmom will vent to me about something, but not do a darn thing to change the situation. I've finally learned to say "we've discussed this, I've said what I'm going to say, now let's move on".
It's hard, and it takes a while for it to sink in, but it works. It's pretty hard to have an argument by yourself.
I know it's hard to accept that your mom is not there for YOU...totally focused on your RAS, but it is what it is. Maybe if mom finds herself being "shut out" a bit because she's so focused on your RAS, she will realize what she's doing. I know that if I get stuck on something and go on and on about it, people just start avoiding me...pretty good wakeup that I need to change.
Hugs and prayers!
Amy