I am sorry you are having a hard time.
I wanted to comment on your WoW friend liking you. Although you have met, you really mostly know each other online. I would worry about any adult that had "feelings" for someone he mostly knows online. No matter how much you don't you don't truly know each other until you spend lots of time together IRL. Also, why would you consider a relationship with some you in reality hardly know? I have had many friends online, some from way back in the Dark Age of Camelot days but I would never say I know them well enough to end a relationship and starting dating one of them. Their online self and real life self are different.
Also, since you are in a relationship I think you need to stop talking to him in game or irl until you are single and over your current bf if you choose to end things with him.
As far as your mom, I would get out of her flat, find your own place and DO not let her run your life. She cannot and should not tell you who you should and should not date. The relationship you have with her is not healthy. You are an adult, she no longer has control over you.
Good luck! I hope you are able to find the path that makes you happy.