Child custody

My ex husband kicked me out two years ago so I left my children with his mother until I could find a work and a job so my children weren't living out of the car like me. I have tried calling him every week, sometimes every day to see if we could be civil and handle this out of court and set up visitations and custody joint. Now he won't answer my calls lied to me about letting me see them. I love my kids and don't well didn't want to take him away from my ex and his family since my boy's have been so close to all of them but i want my children and i am tired of being the nice scared woman. His family has a lot more money then me and they tell me i will never see my kids, i even got so desperate that i tried talking to his new wife but that went no where and all i got was nasty emails from her. How can I get custody of my two boy's?