She probably ISN'T a threat to herself--she's certainly a threat to you, at least in the mental-health sense.
If she becomes the least bit physically threatening toward you--if she destroys your property or hits you--contact the local women's shelter (for battered women) and talk with an advocate about a protective order. That would require her to vacate immediately and to have no contact with you. I certainly don't advise it as an expedient to get an annoying person out of the house, but you have a right to live in peace. No criminal charges are necessary to get an order, but the requirements for one vary from one jurisdiction to another. Usually the court would have to find an order necessary to protect you from "domestic violence"--and in many jurisdictions that includes harassment, criminal mischief, threats to physically harm, etc. Other places there must be physical violence.
Talking with an advocate is free and confidential, and they are accustomed to hearing from male victims.