Does my friend have to pay spousal support if he is in the process of proving his marriage is invalid?

A friend of mine recently got married. Shortly after he found some things out about his new wife that had he known sooner never would have married her. They are in the state of Washington and she had her brother (minister/convict/scam artist/drug addict) and 2 friends fill out the marriage papers with her for the ceremony, and had my friend sign the predated paper the next day. (That makes it a proxy marriage.) After 2 weeks of marriage a divorce was requested and now she is trying to claim that he owes her spousal support. He is military, not collecting a housing allowance and the marriage was not legal to begin with. What actions does he need to or can he take to end this situation because she is harassing him daily?