I did dog rescue long before I had kids, so I probably have a little different perspective on this. If you are serious about this dog, you need to get it and yourselves to an obedience class. This dog has been severely traumatized by being abandoned by the people he loves. He is going to need time to adjust and bond, and, find his new place in your pack. You need to learn about dogs, fast. The dog is challenging your kids for a place in your pack, and he will keep doing it until he learns that he is the lowest ranked animal in the house. This is going to take 1) you learning how to be the alpha and 2) you keeping the children away from the dog until that settles down. Which means you and your husband are going to pretty much have to spend every minute you are not with the kids with the dog until he settles in. If you can't handle the responsibility of learning about a rescue dog (you read books and talked to pediatricians when you were pregnant/had babies, right?), then you need to contact Golden Rescue or another dog rescue immediately. This is NOT the dog's fault. Here are some links to good books:
http://www.amazon.com/Petfinder-com-Adopted-Dog-Bible-She...
http://www.amazon.com/Successful-Dog-Adoption-Sue-Sternbe...
If you do rehouse the dog, however, I want you to think about the message that it send to your children. Pets are an enormous responsibility, and not something we throw away when we move, or get tired of them, or don't want to live up to our responsibilities. Everyone makes mistakes, and, of course, your children's safety is paramount. Maybe you've made a mistake. But if you have, you owe it to the poor dog to find it a situation that will work out better for it, and not expect some rescue organization to swoop in and make all your problems go away.
I really think this can work for your family, and that it can end up being a real blessing to you all. Call a Dog trainer today. Buy some books. Put up a couple gates so you can manage where the kids/dog are. It's going to be a rough adjustment for a few weeks-- just like it was everytime you brought a new baby home. But you can figure it out together!