for him to have up to 4 wives. And there is no means to my knowledge by which he can be made to support you if he really wants to duck out on his responsibility. It is not like you are all in the same country and you can turn him in to the courts for support. This is a problem even here in the Arab world when a man has multiple wives and children and doesn't support them equally. From what I have been told it is up to man to decide how to spend and what the needs of each are.

You are swimming upstream towards a waterfall. You can't get anything out of a man who doesn't want to do right by his wife (or ex-wife) and children. If you have faith then you should believe that God will punish him and you have to build a better life without him.