Is it alright if I don't want my aunt at my high school graduation?
That depends. Why don't you want your aunt there?
First of all she is a bitch and I hate her guts
That isn't a very nice thing to say. It's also not very nice to not want certain family at your important events. You should try and reconcile with her.
I'm tired of her being in my life.
I think you should give your aunt another chance, and invite her to come to your graduation. I'm sure if you talk to her you'll see that she's a perfectly nice person.