Marital problems

I am married to someone whos already married. He promised to give me the same in due time. He hasn't told her because shes got 3 kids and shes gonna leave and doesnt want to lose his kids. He opresses me now after 2 years of sticking by him. He says that he doesnt even know if our nikah is proper when it is. He also says that I'm not his wife. I am really angry and I want to tell the first wife, but I dont know if I should. Now he is telling me that he doesnt want it anymore because his family, his dad and sisters, mum has found out. What do I do?