Did you get the car checked by a mechanic before taking possession? Is there a written agreement? All things any lawyer would need to know before...

The police cannot be sued because they didn't believe you.

You want to hire a lawyer and pay filing fees over $5? Does that really make sense?

The cost of a lawsuit would far outweigh any potential recovery IMO.

Nothing in here strikes me as odd, or any evidence the police were "in on it."

Your parents can report it to the police. Your partner can face a number of different charges.

Google is your friend............................................

The same way you sue anyone. Hire a lawyer, have them review all the documents and pay them to file a lawsuit.

None of us can predict how the lawsuit will turn out. You can return the money and settle the matter.

If mom says no, the answer is no. She can take out a restraining order and call the cops.