My sympathies that you find yourself in this position. I know it all too well. In fact, our situations have a lot in common.
Prepare yourself for when she cycles back towards you. It happened to me and I read too much into her actions. I was totally unprepared to handle it (passionate kisses, a 'date').
Things fizzled with the OM and I think she reached out to me for emotional support. It was a critical time that could have been handled better. Strongly suggest you read James Dobson's Love Must Be Tough. Remember it when the time comes.
Finances: You mentioned this was a major issue. Check out http://www.daveramsey.com for some excellent fiscal advice. It will help you whether you are with her or not.
She can enter your home at will? I wonder if you shouldn't change the locks. You wouldn't just walk into where she lives, so why should she be able to come and go in your home. Thoughts from others on this?
Best of luck to you.
-db
B42, M15yrs, T16, No Kids 8-06: Buying house 8-8: Bomb 8-16: Served 9-11: D final 9-28: She moved out 12-3: PA-her 9-26-07: Last time I saw her. My sitch.