There are a few things that continue to hurt, some of them old, but with the exception of one, they're just filed in "we live and we learn". The one is relatively recent, I probably won't ever need to deal with the person again in my life, and I think I would be able to let bygones be bygones -- I'm just not sure, because it was a very deep hurt and there has been nothing to mitigate it. I'll probably never know.
In general no, I mean I have friends who never let go of some silly insult. On the other hand, if someone really hurts me needlessly (not just a boyfriend where it's just life) I have a hard time just letting it go. So I tend to walk away, not get revenge but get out. I have a few friends I didn't return phone calls for and let them go. I was being used.
I also have a supervisor at work who is undermining me and I can't stand her. I have mutual friends with her but rarely attend events she is at.
It depends on the degree... if someone really hurt my feelings I would hold a grudge but I would eventually let it go but always remembering not to trust that person the same way ever again.
I defineately do. Shame on you if you hurt me once, shame on me if you hurt me twice.
That being said it depends of how bad the situation is and how long we've been friends or family. In other words, a long time friend can get away with a lot more than a new friend within certain boundaries.