What is the best way to deal with bitterness & resentment?

I don't really feel I have the right to express it, because for the most part, it doesn't come so much from being "wronged" so much as it comes from being treated condescendingly and being endlessly mocked by people who have taken care of me, and, for that, I do owe them something. So, for years, I've just been swallowing it, and I think I still can. Still, I'd like to get over it. I'm willing to forgive, and yet it just seems to keep piling up all the time.