Can't be with my girlfriend anymore.
What exactly did she do that made you want to break up with her?
She acted like a slut in front of family and friends.
It was probably embarrassing for you to have to deal with your partner's behavior in front of your friends, but have you talked to her about it? Perhaps she has an explanation for what happened and you shouldn't be breaking up with her over some trivial thing.
She's not going to tell me anything. I need to focus on making money and I don't have time for this drama. My friends don't want this drama either.
I think that's fine. Someone introducing needless drama in your life should be avoided.