The first thing she has to find out is whether the marriage is actually recognized by the State where the husband was living or if it had been properly registered (Most states recognize the validity of legal marriages registered in Thailand but not all of them. To register the marriage in the United States, he must have contacted the Attorney General in his state of residence)
If the answer is no, then no hope for her.
If yes, she definitely should contact an American lawyer to get accurate advices.