"Holding onto anger is like taking poison and expecting the other person to die"
I love this. It's so true, and you can swap out anger for bitterness, resentment, hatred or pretty much any negative emotion.
Recently someone hurt my feelings, someone close to me. I've been angry about it for a few days, I could confront them but I know I'd get one of two responses. Either they'd be defensive/angry, or would take a very negative view of themselves which would require me to contradict them to make them feel better about themselves. Neither of which would do me any good.
I'm pretty sure they're totally oblivious about how their actions have impacted on me. There's absolutely no malice behind it, it's a sin of omission rather than an intentional act. It's not the first by a long stretch, it's not even new, nor will it be the last.
So I have a few choices. I can cut this person out of my life, which isn't going to happen - I love them very much. I can tell them how I feel. I've already discounted the option of telling them.
I've decided I'm not going to continue to hold onto it, but I'm not going to put myself out for them until I feel things have balanced out, it's what I need to do to reduce my irritation and frankly, they don't deserve it. I'm not going to actively hold onto my negative feelings about it, it doesn't do me any good at all. Being the grown up sucks big hairy balls sometimes - ultimately though it's the best thing for me.