Details of that agreement matter significantly. The term “social contract” is pretty meaningless; you need to tell us the details of the agreement to figure out if you might have an enforceable contract. A key question for you is this: what exactly did you have to do under this agreement to get the money? Also, in what state would that be done?
If the agreement was essentially to exchange sex for money, that’s prostitution and illegal nearly everywhere in the U.S. Contracts for illegal activity are not enforceable in court. If it was something else involved, you need to be more clear about it.