COULD I GET CUSTODY OF MY CHILDREN FROM MY EX....?

About 3 years ago I decided to leave my ex , at the time my children were 3 an 1 1/2 years old, I took them with me . I moved into a apartment and was working two jobs( waitress and cashier) . It was during the summer time so my sister 17 years old at the time watched them while I worked.I had my rent and my new car payment plus insurance on my car and utilities to pay for and on my income it was tough. My ex refused to give me any money. After about 3 months I was getting very behind on my bills and was about to have to quit one of my jobs so I could be at home with the boys, due to my sister returning back to school. She was a big help but it was time to make a decision in the best interest of the children. My ex had a very good job and health insurance so we talked and decided that at the time they would be better off living with him due to my financial situation. I was not to pay child support because he said he didn't need my money but we agreed to split costs such as co pays and activities or clothing for the boys. After signing papers , I received a letter from the judge asking us to come to court to re access the situation no more than a month after signing papers. In the court room he just explained he couldn't waive child support by law and would just order 40 $ a week that would not be enforced. so i have been giving my ex 100 $ every two weeks since. but not too long after seeing the judge my ex informed me he had quit his job and no longer Had health insurance . it was in the divorce that he would provide health insurance and there were other things in the divorce he was to up hold like for example the trailer he and the children were living in was in my name but he was to keep up the payments and there was a loan on his truck in my name that he was to continue paying. none of these obligations of his were meet. my trailer was repoed with out me knowing until i received a lawsuit and i also received a notice that the loan was delinquent. anyhow i remarried in June of the next year and i live 50 miles from were the children live , i see them every other weekend and 3 weeks during summer and 2 weeks at Christmas and 1 week during spring. it has now been 3 years and the children still do not have health insurance he does not take them to the doctor when they are sick and he does not brush there teeth or clean there finger nails and keep them clipped. my husband and i have health insurance through his job at the sheriff's department but are unable to get it on the boys because they don't live in our house as we have tried. i have also tried through all kids and medicaid but have been turned down because i am not ordered to have insurance on them. i have told my ex this and encouraged him to try with medicaid and all kids but he still fails to do this. he is a loving father but i do not feel he has the boys health and interest at best. i feel that i can provide for them more now that i have straitened my finances out . i now live in a house that is paid for and have two vehicles one that was just recently paid for . i have never been on drugs or in any legal trouble. i am a good mother and these three years have been the hardest i have ever endured. after talking to the boys over the phone , when i hang up i just find my self in in tears as i do when i drop them off at home. after knowing all this do you think i have a chance at getting custody of them from there father.