What's going on?
Most Helpful Guy
She hates you because you have had a prior relationship with the guy. Additionally, the girlfriend is assuming you still have feelings for the guy.0
Most Helpful Girl
... I live with a guy...
I see a bit of a green eyed monster here, dear, and i don't know if she knew of the past that used to be a blast, but regardless of That, the writing on the apartment wall and all is telling me that no matter What 'girl' is living under this cozy roof, she is Not going To... Like and has this Spike.
Try and make the Best from the Rest of a Bad situation. Just be as pleasant as possible, don't overthink anything when she is there, and if she always appears with a hair crosswise, it is Wise then To... Split the scene and make absence make her own heart grow fonder.
Good luck. xx0