Hello everyone, newbie here. 
First off, I apologize for the length of my post, but if you can bear with me, I'd be super grateful. I really need advice.
I have a question related more to my wife (who suffers from pretty bad depression/anxiety/possible OCD), rather than myself.
I find that a lot of the time I have trouble convincing her that I'm telling the truth. It's not about huge issues or anything, but rather about mundane things. 
For instance, it could take me 30 minutes to get dinner ready, but when I come in she'll swear it was a whole hour or more, and then be utterly convinced that I've just been wasting time. 
Yeah, that probably sound silly and childish, but over the years it's started to really get to me (we've been together 8 years). 
Especially in instances where I bring her categorical proof I was being truthful, and then she seems to go to extremes to disprove what I'm showing her, and prove to me that I'm definitely a liar. 
I find myself thinking that possibly because of her depression (coupled with deep self esteem and self image issues that I know she unfortunately has), it's more comforting for her to have this kinda martyr-ish narrative where she's a great wife (which she is), and she's married to a lying sack that she puts up with.
She's frequently told me that I always come off as the "good" spouse (as though we were on some messed up reality tv show and I were "winning"), so I think there might potentially be some truth there?
I feel so insanely guilty even asking about it here, but I'm honestly out of ideas as to how to approach this. I know I have to try and take my ego out of the equation and not to take it personally if this really is a depression issue, but it's damned hard.
I've run the gamut from getting angry (I know, not exactly mature of me, and I feel bad about it), to just sort of giving up and letting her believe whatever she wants. 
The problem with this latter approach is that I'm scared that this'll end up damaging our marriage (without me even doing anything).
I've tried reasoning with her. I've tried telling her that (like pretty much everyone else in the world) I've told little white lies (on the scale of "oh yeah, I took the trash out" when I hadn't, so nothing earth shattering), but she just throws up this super black and white, "lying is lying, and therefore you're a pathological liar" logic.
I know this is super long, but I'm honestly really lost here. 
This woman is the light of my life and I can't imagine my life without her, and I'm sincerely scared that this could hurt our marriage.
Any help or advice is GREATLY appreciated.