1. You can sue, assuming you have a contract
2. The question is, is it worth spending the money to get a judgment if she has no assets to go after (i.e. are you spending good money to go after bad) - and that is a question you have to ask.
If she has a home, you may wish to sue, win, then put a lien on and wait until the home is sold (assuming equity is there or will be there).
This is just general information. Without seeing paperwork I can't give specific advice.
Good luck with your situation.