If you had sole exclusive possession you could eject a guest at any time.
You don't, so you have two legal ways to approach the problem and a third non-legal method.
One legal method is quasi-criminal, the other civil.
Criminal - Breach of the peace. Call the police and have them remove the angry person. Ask about getting a restraining order if you feel threatened by this person.
Civil - Your rights are to be able to have the quiet enjoyment of your property. Being in a share house complicates this right. You presumably both have joint exclusive possession of the property. Having exclusive possession means you can both eject someone who is trespassing using reasonable force in doing so. You can't call this person a trespasser as this person has permission from your housemate to be on the property. You cannot revoke this permission by yourself. To take action you would need a court case and have to prove a private nuisance. Not easy, and likely not cheap.
Easiest solution is get the house mate to agree she should leave, then you can legally eject her. Probably a good idea to record the housemate's agreement
If your housemate doesn't agree, police is the next easiest option if you are afraid of what she may do. If this is not an option, then tell her you'll take her to court for disturbance of your quiet enjoyment of your property. Put her on notice and see if she behaves. If this is the path you choose, record all instances where your quiet enjoyment is not possible.
Third option is not a legal solution - just be obnoxious to her. Stand in her personal space, without touching her and without being threatening in any way (eg read a book while standing next to her). It is your house and you can stand where you want in your house. Be rude and offensive. Put a lock on the toilet door. Turn off the TV if she is watching it, turn off the music if she is listening to music. Do not allow her use of your personal property (eg couch, kitchen table etc).There are a myeariad things you can do if you put your mind to it. The complication here is your housemate and what they consider is appropriate.
Good luck.
