Note that I am not licensed to practice in your state.
If you haven't done so already, you need to go file a police report in regards to the identity theft by your ex girlfriend. After you do that, then with the police report, you can contest the charges on each of the credit cards and also on all 3 of your credit reports. Know that this is a long and slow process and may take a while before all the investigation is complete. However, if you have the police report and you open an investigation with the card companies and the credit bureaus, they must do an investigation for you.
If that does not work, then we look at other options. The 7 year thing you're talking about is probably the statute of limitations for debt collections. The law is not that after the statute of limitation runs, you dont' owe anything. The law says that IF THEY DO NOT COME AFTER YOU WITHIN those years, then they can't come after you at all afterwards. However, during those 7 years, they have the right to sue you, garnish your wages and put a lien on your home.
My suggestion would be to first try to deal with the identity theft issue first and if that doesn't work out, then speak with a local bankruptcy attorney.
If the house has already been foreclosed and the car reposed, bankruptcy will not help you. Additionally, the bankruptcy will remain on your credit reports for 10 years. The record of the foreclosure and repo will come off your record in 7 years. The statute of limitation is 4 years to sue on debt.
In Texas, suits to collect the unsatified balance on a car note is an unsecured debt and likely to be sold. It is very possible to defeat such suits.