Child Custody....Again.?

As stated in previous questions. I have been divorced from my ex husband for about 3 years. We have two children together. During the past three years, he has disappeared, (we live in NC), for weeks on end, going to California to help a friend grow and harvest weed, he took several trips to Michigan. He would disappear and not see his kids for weeks, sometimes months. Child support was another battle. Some weeks he would pay $100, others $20, sometimes I wouldnt see child support at all, the longest time span with none was 9 months straight. When he was, in town, and it worked for him to see his kids, I would take them, pack all the clothes, and go pick them up. He doesnt have a license and is "self-employed". He was living with "friends" I went to get the kids on several occasions, and found marijuana hanging in the kitchen, pipes on coffee tables, beer bottles and cans everywhere. He finally agreed to only watch the kids at his dad's, however the children tell me he sleeps in, they call me at 1, 2, 3am. They tell me he doesnt fix them dinner. Nothing. I recently got remarried to a US Marine. I called my ex to explain, that we would be moving on base. Which is 6 hours away from him. Suddenly after 3 years of this behavior he had an issue with it, and threatened court. I offered to bring the kids to him every school break he agreed. We moved, the kids love the school, their grades improved, money isnt an issue. Their father stated he would call them all the time. In 7 weeks hes called 3 times. He also wants me to reliquish him from ever paying child support again. 3 days ago, I took them to him for school break as promised. Tonight my daughter (12) was left at home with no adult, she cut her bangs, and dyed her blonde hair pink and black, with material my ex-husbands girl friend bought her. My son (9) was with my ex and his girlfriend at a party out until 1:15am. My daughter had not ate dinner, and when I called my ex he said all was normal. He claims I had no reason to be upset with him, and that he was a great father. And if I continued he would go to court and sue for full custody, and get it. He said my daughters actions we my fault, and that I had uprooted their lives and he could get full custody no problems. My basic question is, my husband and I are very concerned about the childrens well-being with him, and want to know if it seems possible for us to achieve full custody, or possibly even my husband adopting our kids. My ex is unstable, does marijuana, admits openly to doing LSD, and mushrooms, has no license, doesn't pay child support. and hasnt shown income in 3 years. Is there anyway we can get full custody or rights to these kids?