@Ms Spock I have had this same issue, but I have thought of it as hiding in plain sight instead of a lying problem.
I'm in in person therapy more often now and it's been one of the hardest things for me to deal with because its been a lifelong ingrained survival issue. We werent given choices about whether it would be okay to disclose abuse or not, we just knew it wasn't okay to be honest.
Not feeling authentic with anyone, even my closest friends my entire life, because there were reality ' no go zones' had made me feel invisible and like a fraud a lot of the time.
Mostly my habit wasn't outright lies, it was altering things to be somehow sideways from where they really were.
An example would be, instead of telling someone my first car was an old blue volkswagon, I'd tell them it was an old green volvo. Both German cars and similar color. I'd tell someone I went to college, but reverse my major and minor degrees and say I went to the school my best friend went to instead of mine.
On the rare occasions someone caught on to this, I felt total humiliation. Its impossible to explain why you'd do something like that and it made me feel stupid. I may have out grown that if I hadn't married someone that also required constant deception to live with, but maybe not.
I feel total exposure and vulnerability when I disclose sometimes simple facts that are totally mundane. Its painful, and the weirdness of it makes me feel crazy and hopeless.
Sometimes the more personal facts people know bother me a lot less than if they figure out I had toast for breakfast instead of cheerios. Its not a carb issue, why the hell didnt I just say cheerios instead of changing it to toast? You dont want to be a grown up and look someone in the eye who just realized that you did that! The humiliation doesnt keep me from doing it again though.
I'm hoping this helps you, because I dont feel any differently than you described, even though I haven't been in the habit of lying about many factual circumstances for the last decade or so, I still have a knee jerk reaction to alter things and it makes me feel secure when I do it.
The shame isn't about the lie itself or that you said it, its that you feel like you're not allowed to be authentic, and then are shameful for not forcing yourself to be authentic anyway. The content of what you're not honest about doesn't matter, its the feeling like you're a shadow hovering around your real self and only you know that. That you are not welcome to be here and fully present.
I flipped out on a thread here when someone attacked my credibility because of that, thats the truth. I rebounded by changing my avatar to part of my face...then offered up my children's faces without asking them first LOL.....
I hope you stop being so hard on yourself about this, you didn't ask to develop de-realization coping skills to survive trauma, and where you're coming from with this habit is not intentional deception. That is not what motivates you. I work with people that lie at their job all day and think its funny, dont put yourself in that category Ms. Spock, you don't belong there.