Dear Stuck,
Hmmm. Is anyone out there in Internetland shocked that living with an ex has turned into an ugly situation? Not only had you already broken up with this woman, but she wasn’t able to make things work in her last place. Sounds like a great choice for a roommate. I’m sure you won’t make that mistake again.
But enough scolding. I’m sure you were trying to do something nice for her and for her kid… so here you are, stuck with her in your house. First of all, you definitely need to consult your local regulations about housing rules. If she is paying you rent, you may have to give her a 30-day notice. Which would be the respectful thing to do regardless of whether you are legally required to do so (and no matter how much you can’t stand her).
Have you made it undeniably clear to her that you want her to leave? Not hinting, not asking nicely… But saying it straight out, something like, “I’m sorry, I know it upsets you, but this isn’t working for me. You are going to have to move out. I will give you until 30 days from now to find another place.” And whether you are required by law or not, I suggest you put it in writing as well.
I’m not sure what you mean by confrontational, but whatever her reaction, just stick to your statement. She can yell, scream and call you names, but that won’t change your decision. Remember, she is fighting for shelter for her kid, not just for herself. For her, the thought of being homeless will drive her to do whatever it takes to keep them safe. Your role is to let her know she has to do that someplace else.
Do you need to call the cops? Hopefully not, if you give her a deadline and allow her some time to find somewhere to go. But if she's that stubborn, you might let her know you are not afraid to get the authorities involved.
Good luck!
Humbly yours,
Issuesgirl