Divorce from abroad

Hi everyone. I am looking for advice on how to divorce my wife who is in Vietnam. I am in the US. What are the steps I should take to do this? I searched all over the internet and nothing explain how I should be doing this. A little back story about the situation I'm in. I met the girl online and we speak for close to 1 year. In the beginning she was very soft spoken and nice. later down the road she persuaded me to come visit her. I went to visit for 2 week because thats all the vacation time I have from work.  first week was very good. we have lot of fun going around. she say she want to be with me and we must get marry. we do paperwork. everything is good up to the day I leave. she come with me to airport and her friend at airport waiting with kid. she say that is her son. I did not know she have son. I am shock. I come back to the US. Now I getting call from her to rush paperwork here in state. she and her friend call and ask for money. I don't know what to do. can someone tell me what I do ?