Nannabee, I can really relate to this. In fact, I have out right told my T that sometimes it feels like I am lying and manipulating him. For me, I think it has a lot to do with two factors:

1. A fluctuating narrative of reality during my upbringing with a probably narcissistic primary caregiver. I was told reality wasn't true and things that weren't true were and you had to live within that construct in order to survive. Whatever her reality of the day was, buying into it as completely as possible or at least trying to overlook the glaringly obvious inconsistencies, was the safest possible way of coexisting. I was also threatened when I attempted to assert my version of the truth, so there is a protective part of me that constantly denies "dangerous" realities by convincing myself they might not be true.

2. Dissociation. My perception of things that happened having been true and even my feelings about them being true is so transient. So, I will be near crisis one minute and completely numb to my prior distress the next. So, it will literally feel as if I have lied about things that happened or my emotions, because I am completely disconnected from "whoever that was" that felt that way. If I try really hard, I can sometimes remember that I honestly was that scared or sad or anxious in that moment, but it doesn't FEEL real or true. Rather, I intellectually know that it was.

Anyway, I don't know if these reasons resonate with you at all. It took me months to sort out exactly where some of these internal "lying" and "manipulating" and "drama" and "attention seeking" messages came from, but many of them are straight out of the mouth of one of my abusers and I internalized them so long ago that it just is a part of my world (and self) view...that to try to speak up means I am bad, because I am misleading or trying to get attention. But, that is a bit ridiculous, because I know (objectively) the things I've said aren't a lie and if it was someone I cared about, I would tell them that bringing attention to something that needs to be addressed and fixed is the absolute best thing to do for healing and growth...

Funny how it doesn't apply to one's self, though.