I let a girl stay in my apt. She started paying after 3 mo. How do i get rid of her?! I already asked nicely!?

I dated this woman for three mo. and stopped after I noticed her jealous nature. Right after that she called me saying that she needed a place to stay because her Aunt kicked her out. I said no. She texted me 30 times! All saying that she had nowhere to go and "how could I be so cold?" So I finally relented and picked her up. I told her she could stay the night and use my phone to actually call someone (she only had texting ability). After months in my apt. and many negotiations, I realized she wasn't leaving anytime soon and she was quickly making me more broke than I already was; so I ask her to pay weekly until she found a place. It's 6 mo. later and she is getting confrontational and won't leave. I have asked her to leave repeatedly and now she is threatning me legally. How do I get rid of her?! She has paid the last few months and receives mail here but she is not on the lease and things are getting very hostile. I want to do this with as much civility as possible.