<human>: They have been together 5 months, moved in after two. Tumultuous relationship where his aggressive behavior got worse and worse. Several altercations later (in witch he threatens to kill/stab/beat her and smashes the kitchen) and broken promises it wont happen again. She resolves the relationship is over and its not going to get better.

He calls sobbing begging for forgiveness or switching to rage where he calls her all the names under the sun. The issue is they rent a house together with 10 months left on the tenancy and our father is the guarantor.

The ex boyfriend is refusing to move out and end his tenancy there. Has anyone been through this, or has had experience with this situation? She thinks she is the lead tenant?

Looking for advice on:
keeping her safe, 
possibility of switching the guarantor,
any advice on the tenancy.

Provide a brief overview of the text.
<bot>: Sister and her abusive SO are breaking up but he won't leave their rented property. Our father is the guarantor.