I may have inadvertently ruined my best friend's life
How did you ruin their life?
I got her into some trouble.
Mistakes happen but it is okay to feel guilty if somebody got hurt. Even if you didn't do it on purpose, you will still feel bad that they got hurt.
I'm not getting it. I don't feel guilty at all, she's an annoying bitch that needs to get over her issues
That's no way to treat a good friend. You should cherish their company and want to be there to help them. If you had a disagreement, then solve it with it in a sensitive manner and give it time.