I'm going to go off on my girlfriend
Why would you want to yell at your girlfriend?
She was being very rude to me, she's trouble.
It's not nice to be rude to someone, but going off on them doesn't solve anything. Have you tried talking to her? Maybe she has a reason for being rude to you or perhaps she didn't realize she was being that way.
She knew, I told her to stop being rude and that I don't like it. She ignored me and I felt like I had to go off on her.
It is understandable to be upset when they are ignoring you but you shouldn't go off on them. It will make them less likely to want to be around you or to have a conversation with you.