Did he (the landlord) tell you how he was going to be sorting it out? Given that you were on the premises first does this give you any advantage? Sorry to hear that this seems to be deteriorating for you. Wish I could help you.

I dont know how hard it is to evict tenants where you live. It can take months where I live. Maybe your landlord can issue some kind of formal warning? Silly him for thinking he was being smart.

Why can't you have a chat with your housemate? (When she is out of the house - and why cant they go to her place sometimes?)

Thinking of you.