<human>: I realize this is slightly different than the normal problem addressed within this subreddit, but I appreciate any help or advice.

So, here's the long and short of it:

I (22/m) have some friends (2- male and female, both 22) that make me unhappy. We've been friends for a bit less than 10 years now. I've spent a lot of time beating myself up over their opinion of me and trying to be better for them. But I've slowly started to realize that I am not the problem. I have friendships with others than have so much less drama and work out fine. They're both amazingly petty, passive-aggressive, hateful, and overall make me feel like crap. These friends of mine are dating and soon-to-be married to each other. I am supposed to be a groomsman at their wedding and am also planning both the bachelor and bachelorette parties.

My question is this: how can I end this friendship or at least withdraw heavily without completely burning bridges and, preferably, not be a part of wedding I don't support?

Could you distill the essence of the text into 1-3 sentences?
<bot>: Thought I had problems, think it's actually some bad friends who make me feel like crap. Don't want to be around them that much anymore. How can I do it gently?