Whether you're writing a blog, a column or your autobiography, you're likely basing at least some of what you write on your opinion. Which opens you up to criticism by those who already know you along with those who wouldn't know you from Adam (or Eve for that matter). Perhaps they're jealous that you're a writer and they suck at it. They could simply be the type who has to crap on everyone's parade. Or they're the one who never quite remembers things the way everyone else does. I call them them the naysayers, deniers and pains in the ass (I did notice that my plural in the headline seems off - shouldn't it be PsITA?)
For instance, a friend of mine said I made her sound like a bitch in a piece I wrote. It was not meant to be published (and still hasn't been, though maybe I'll throw it on the blog one day for shits and giggles), rather it was something I wrote for personal reasons. Actually, I thought it was humorous. But she was clearly not happy with my portrayal of her, even though it was my truth. I love her to bits, but I'd say she's a bit of a denier.
And now that I think of it, my grandma was a bit of a denier too with a similar style of piece I wrote. That one wasn't for publication either. It was one of a few stories I put together for my grandma. My mom actually told me not to include it in the collection. I did some edits which better explained grandma's frame of mind at the time in question, but I kept the story in there. Hey, they're my memories, after all.
However, the goal of the story was to make grandma laugh, not cry, so with some minor changes, it was suitable for reading by family members. Grandma still claimed to not remember the incident in question (the crux of it was she told my sister, "Make your own goddamned lunch" when we were kids - I'll post the story here some day so you can read it for yourself) but she was entertained nonetheless.
The question of what to do when challenged by family or friends on what you write came up a few years ago when I was teaching a night class. The course was called "Turning Personal Anecdotes into Publishable Stories" (yeah, kinda wordy, I know). Anyway, I told my students the same thing I'll tell you: if the story is important enough to you, write what you need to write. If it's going to feel good to write it and you know it's a good story, tell it. Once you start editing out of fear of what other people may think, it's no longer your story. And it loses everything that makes it special.
End of story.