Unlike exaggeration or embellishment, or even denial, this is seems beyond just " taking it all with a grain of salt." It is the character, the core of these people, that will force of reckoning for you.

Your experience reinforces my reasons for the plans I have made with my two closest friends regarding my memorial service after my death. I am all too aware of how common it is for people to take advantage of the situation following someone's death to put out a lot of self-serving, phony baloney stuff at the memorial service or on online obituary sites, where they revise history to pretend like they were chummy or admiring of the dead when the reality is that they were despised by and estranged from the dead person. While I know there is no way to prevent someone from trying to do this with online obituary pages, the people I trust, along with the funeral home, can easily remove these kind of condolence notes once they are spotted. As far as the memorial service, I am particularly concerned that my siblings, who I am estranged from and have little contact with, might try to use an open sharing period in my memorial service to revise history or pretend to have been supportive or caring for me during my life, when that is anything but the reality. So my trusted friends will only have the people I have designated be allowed to speak at my memorial service. It's sad that people cannot be honorable and honest even after death, but I will do what I can before I die to prevent this kind of BS around my death.

Even when there's no possible gain of prestige or wealth a group of people all seeing the same event will describe it differently.

I think the majority of people tried to put their own actions in the most favorable light. I know I do despite the fact that I can't stand liars. I'm only human and it's not unheard of for me to fudge a little bit. Or at least leave something out.

When I was six my Father beat me with a belt for a half an hour while I was naked for telling a lie in an attempt to not get in trouble, you can kind of see why I didn't want to get in trouble I think.
That was 1965, he hurt me so bad I'm still hurting today at 62.
Imagine how it felt when I went to work with him after I got out of the Navy on the oil platforms in the Gulf of Mexico. He was a cook and I was a galley hand.
Dad would talk to the other people working on the rig and it was just one lie after another.
I couldn't lie that much if I tried.
Dad was a conservative and a Luddite, and he never knew what a Luddite was, they never do, which means he was an alien species to me.
Thankfully the old bastard died in 2001 of colon cancer and I think he got off too light.

Ok, you asked for suggestions... so please accept this in the spirit of helpfulness with which it is intended.

No one escapes human nature; not me, not you, not them. I am certain they are as completely unaware of their narrative distortions as you and I are of our own. H.sapiens is a creature that lives, most directly, in a protective encasement of narrative. Its function is not to align with objective reality, but to provide an interface between ego and harsh reality. If those folks were to hear your narrative - your very most sincere and heartfelt “truth” - they would no doubt be just as aghast. None of us knows reality. We know the bits of reality and the bits of fabrication that our egos can tolerate.

“Oh but mine is true!”

No. It isn’t. Nobody’s is true.

Everybody thinks theirs is true.