My ex husband has never paid child spport right we have been to court 4 times where he was ordered to pay the back child support in payments in addiion to the lowering of his child support. Today he owes me over $20,000 in back child support. He pays a portion or nothing of what he owes monthly but never close to what he is supposed to. I ask him for help and he just does not. He moved to Florida 9 months ago and has not attempted to see our 2 girls (4 and 10), he calls them once a week and the conversations are about 5 minutes. He is married now to a girl with 3 children and she does not work. I don't care about that except he is supporting them and not his girls.
He is now asking for me to meet him half way for the girls to visit with him this summer probably a week. This would be a total of 20 hours drive time to meet to take them and pick them up for the girls to visit this summer. The girls do not want to go, they don't have a connection with him. I think they need to get to know each other again and he should come here to visit with them.
My questions are --do I have to let them go across state line? And do I have to meet him half way?

Does he have a visitation order? Was is modified when he moved? Those are two huge issues at hand and our answers will depend greatly on the answers.

His visitation order is every other weekend and 3 weeks non consecutive in the summer and times on holidays - but that is when he lived here. It was not modified when he moved.

Well, until the order gets modified then he is still entitled to the visitation as stated. Since he didn't take it back to court you can. He will still get visitation but most of the travel cost he will generally have to pay because he is the one that moved. Also because of the great distance it may or may not remain every other weekend and the time in the summer will more likely become consecutive weekd. However, those things are all up to the judge. I don't have your order in front of me so I don't know what it says about travel so you should probably get a court date to have it modified based on the grounds that he no longer lives the same distance away.