A tough situation to be in, for sure. I've got to "cop out" and direct you to an attorney as well. How the rental agreement was handled, and how the money you were owed was secured will dictate your recourse. If she's not paying a rental agreement you should be able to evict, but I'm not sure if there are any other requirements imosed via courts/divorce etc.
By all means don't let it get to the point that it affects your ability to pay the mortgage. Maintaining your credit is essential right now, as lenders of all types are looking for quality first, second and third when reviewing loan applications.
I hope you can work this out quickly and effectively. Let me know if you need any recommendations on attorneys in our area- I'm from Benzie County as well.
You could try asking here...http://www.avvo.com/ ...A legal forum where lawyers answer the questions..
Good luck, Dunes
Nice of you for 6 month lack of payment