I was blessed with the opportunity to share this with a kid from my parents church that was in the middle of a fight with his cousin and i figured it couldn't hurt to share it over here.
nick, you've only got one family, so nothing good will come from keeping grudges over things that don't matter much (i'm only assuming that this is the case - if it is a big issue, then y'all should still try to work it out so that when you ask her to pass the stuffing on thanksgiving, she actually passes it LOL).
more importantly, as a believer, you should also aim for reconciliation. Simply put, God forgave us in spite of the sin that we've committed and his love will cover the sin that we will struggle with in the future - so then how can we *not* forgive someone else who may have wronged us?
One reason that we have been forgiven is so that we can forgive others. Our right response to Jesus' love for us is to try to love others in the same way (selflessly, sacrificially). Not because they deserve it, but because loving others in that way honors the Lord.
no matter how you feel, sometimes it is going to be on you to be the person that is going to take the first step towards reconciliation. And if the other person doesn't want it, you can always try again.