Firstly, what a ****** thing to do to someone! It's no wonder you're hurt and angry.

I don't think you should just ignore it. If he apologises when you see him, then great. Maybe something happened or was said that left him feeling hurt?! As it would benefit the kids if you have a friendship, can I suggest asking him round for a coffee when the kids aren't around so you can both have an adult chat about it?

As it was uncharacteristic behaviour he deserves a chance to explain his behaviour. Having said that, it's a possible sign of the way he handles some situations and you wouldn't want that behaviour in a long-term romantic relationship.