Remarriage without divorce!!!?

My husband who doesn't live with me for almost 4 years, lives in Bangladesh and I live in NY. He got married 6 months ago. I just found out today through a friend. He sent me his wedding ceremony pictures. I am still married to him. I have US marriage certificate. He never divorced me, since he would have to give me the dowry. He always wanted me to give him divorce. Which I couldn't, because divorce cost a fortune. Now he is married 2nd time, without letting me know. How do I take action? Oh, We have a 5 year old daughter. He never paid child support for her either. I am pive and always let him go to maintain peace. But now, I think its too much. He is living in heaven putting me in hell. Guys help me with your suggestion. Should I just let him go, divorce him or I should sue him?