Wow. I'm rarely at a loss for words but I will say this...summer camp is great for kids- I think it's wonderful that you have been given this opportunity for your girls. It sounds like you plan on sending them despite his protestations-- good for you. And like dandy said, let him take you to court if he objects..
He sounds like a desperately unhappy sack of crap to communicate to another human being like that, esp. to the mother of his children. I'm so sorry.