[sc_rufctr]

Sorry Jeff but based on your OP there's not much you can do.

The biggest problem is that she doesn't want to cooperate with you. (based on your OP)

Talk to a lawyer it it makes you feel better but if you tried to force her to pay using your lawyer you would chew through another $7500 before you knew it. Even then it's a crap shoot.
There are other options. Maybe a mediation service might help. But again she has to cooperate and why would she do that?

Maybe put it down to a lesson learned. A very expensive one I know.

I feel for you. I get so pi$$ed when hard working people are taken advantage of.