<human>: Can you give me the gist of the text in a nutshell?

**Backstory:**  My sister has been in a relationship with her boyfriend for a couple years now.  Since dating shes been in and out of the house and keeps my mom worried up at night and a couple of times they've been in really bad fights.  One where they broke the bedroom door in a room they used to stay in and trashed the room and another where the boyfriend had a knife.  Another time where he kept the keys to the car and eventually we had to get rid of it to prevent him or her from doing anything more with it.

**Current:** Hes back here now, and i am sure he'll be staying here despite me and my mom's wishes.  Shes tried to evict him and her before but now that theres a child involved she can't exactly kick both of them out and i'm afraid that if he gets kicked out that she'll follow him and similar events will occur but if he stays here that surely can't be good as well. I'm not entirely sure what to do but i am tired of this reoccurring issue and i want it to stop for the sake of everyone involved here.
<bot>: Sister has a bad boyfriend/relationship and i want to know how to get him out of the house and possibly get her away from him for good.