I'm going to have a heated argument with my housemate's controlling girlfriend.
I feel this is a bad idea. Why are you going to argue with your housemate's girlfriend?
She's very controlling and has taken over the house. She doesn't live here and it's not right for her to act like this.
I'm sure her behavior is very frustrating for you, but you should sit down with your housemate and his girlfriend and discuss your issues calmly. If you start an argument with them, you'll have a difficult time making your points. Discuss your issues and find common ground that you can all agree on.
She's a bad person and I hate her.
I understand that but arguing and being angry is not going to solve your problems. Being the calm and rational person will most likely win when talking to your housemate.