I'm not going to let my housemate break her lease
Why won't you let her break her lease?
She let me borrow her duvet and bought me food and drink
It's understandable to not want a roommate to break their lease, is that can negatively affect you as well. You have to take situations like this on a case by case basis, and if she has no choice but to break her lease then you need to be more understanding. Help her and find a new tenant to take her place.
She broke her part of the lease and it's annoying, what's wrong with you telling me that it's not a big deal.
Even if you make her stay in your house, do you think you guys will be able to live peacefully? I'm sure you'll be able to find someone to take her spot so let her go.