Depends what it is. If its just DH being stupid and pi$$ing me off, then I get over it pretty quick.

If its a friend or online saying something that offends me, I move on pretty quick from it.

If it was something done to me, or someone abusing my friendship - I don't hold a grudge, but I don't hold any respect for them, and therefore will have nothing to do with them. I harbour no anger towards them, its more like indifference I suppose.

If its something done to my children - I'll rip their friggin head off. Then they'll probably hold a grudge against me!