It's hard to face up to that, to write through it, and especially to do so in a way that isn't lessening it, mitigating whatever happened, making it less embarrassing, more forgiveable. The goal shouldn't be for forgiveness, or liking. It should be purely for clarity, for honest understanding, for empathy. I think most people who keep online journals (which are just another form of creative nonfiction) know that urge -- to tell the story in such a way that you come off well, better than you did in real life. And sometimes, you just shouldn't come off so well. Sometimes you act like an idiot, like a fool. It's hard, to be okay with that, to write it down anyway, and let other people see it.
I'm not particularly good at this yet. Poetry helps, oddly enough. There's a part of my brain that seems to think it's okay to say all kinds of things in poetry, admit almost anything, in a way that would be much harder in prose. Maybe I should write all my essays as poetry first...