That's a long one, that, but good question. Basically when they ended he had gone off with her friend, knocked her up but also knocked up some random girl too. So he has 5 kids... nice. He's in the RAF and currently serving in Afghan presently but hasn't the best past.
We do all we can to try and keep the contact there because it's not down to us to tell the kids he's a bit **** (understatement but you know) but it's down to them to work it out and unfortunately be there to support them. The eldest recently didn't want to speak to his dad on the phone and said he didn't want anything to do with him as he never bothered (so hard to hear from an 8yr old) and funnily enough he booked a flight (he was on leave at the time) and we said he could stay with us for the weekend to try and build bridges. Our eldest made sure he knew that it didn't mean it was all OK now. Since then we hoped for more contact but it's still sparse, but I think it always will be.
They call me Dad and have done for a while now and I always say I'm happy as long as they are. They'll always be my boys.
Always hard though. You want to do your best for them and stop them getting hurt but it's not always possible.