Fuzzy,
This is a GREAT question that I've struggled with my entire life...being a survivor of abuse...fearing not being believed...going into defensive mode really quickly.
So far

I've learned, and chosen to hold on to, this...
I can't control what others think of me. I can try. I can wear myself out trying, in fact. That just gets me into a deeper depression/anxiety.
That said, I think there's a huge difference in explaining myself and attempting to defend myself. I try to do the first, but if the other person isn't "getting it", it can quickly turn into defending myself, and I'll back away...for myself.
I think the line should be drawn with most of those mentioned above to a "damage line". I ask myself, "Is this causing more harm than good?"
KD