I think children need both parents, even after the parents have divorced, as long as neither parent is abusive, addicted or mentally ill. Given the ages of your girls, I think you should move close to them and let them know that they are the most important people in your life. That even though you left them for a little while, you love them more than life and you will never be far from them again until they're grown up. (I am actually praying that this is how you really feel, because they'll see through it if you don't mean it.)
What's the custody situation? Do you have visitation? I fully realize that religious issues are going to be a terrible impediment to your relationship with the children. They are going to be told that you're part of Satan's world, that you're going to die at Armageddon, that you're "bad association" and that you've "left Jehovah." It will be up to you to let them see BY YOUR ACTIONS that you are just a loving, caring human being who is their Daddy and who thinks the world of them NO MATTER WHAT.
What you do have on your side is the headship principle, which means that they will have to respect your right to teach them your religion in turn. You might want to skip a family Bible study, but still pray before meals and at bedtime for the time being. Since you are a born-again Christian, I suppose you will eventually want them to accompany you to church. But, please remember how much this might freak them out -- I remember it being weird as an adult to go to one of "Christendom's" services, and my daughter was totally put off by the crosses as I recall. However, because most churches have fun and wholesome youth activities, you might want to bring them to picnics and dramas and such, so they can see for themselves that there is more than one way to worship "acceptably." Please remember, too, that "born-again" can be a quite-rigid place to be coming from in its turn, so imitating the God that is Love might be the most important thing.
out