I'm going to break up with my gf after she forced me into a lifestyle that I hate
Why would your girlfriend force you into something you don't like?
She wanted me to stop playing video games.
That was a terrible thing for her to do. It is wrong to force someone to live a certain way because people should be allowed to be themselves. You should tell her no and let her know this isn't making you happy.
I'm going to tell her she's a stupid bitch and that I just want to get back to winning.
You are right to be angry with her. Just express it tastefully.