I need help to win time with my children

After 18 years of marriage and having three children together my husband demanded a divorce after I had to deal with mental issues of depression and anxiety having moved 21 times across the country for school and his job. I was not able to be settled in one place long enough to get a handle on my condition. This resulted in having doctors give me different diagnosis.my husband said he did not want to deal with this in his life. After our divorce was finalized he remarried a month later. He received custodial rights of the children, and I received non custodial parenting rights until I proved my medical condition was stable which I then would receive 50/50 custody. He is now refusing this parenting plan he agreed to. I have worked hard with my doctors to become stable and now want time with my children other than the few visits I get. My ex  no longer wants me in the children’s lives, I do not have the funds for an attorney. My ex has money and I do not, I need help to fight for my children that I love and want to be in their lives that I feel he is trying to take away from me.