How much time do i give him?

He's probably snapping at you because he's upset about his Dad, its unfortunate but that's the way a lot of emotions tend to come out.He was obviously hurt by your relationship ending, but if his Dad is in that bad a state, he probably doesn't want to deal with the drama of going over it all again and reconciling right now. I would consider dropping the subject of your relationship for now and trying to just be there for him for support while his Dad is ill, and see where that goes.If it doesn't work out, then I'm sure you'll agree that his friendship is better than no relationship at all.Good luck xxx