It's already gotten out of hand. Rental properties are a business and as soon as I learned that and started treating it as such, my life was much easier. You need to start sending her formal letters like a pay or quit which means pay all of your back rent or move out. Don't give her a lot of time because she will probably never be able to catch up and you will be out of more and more money as time goes on. She doesn't need nor can she afford your place. And when you are looking for new tenants please do a credit check on them. Read this forum... it's VERY important.