Turmoil over petty things

Why do I feel so cheated?
I did a favour for free, and all I've been getting back is complaints.
Apparently after I house-sat and dog-sat for last weekend, the living room was stained with pee.
She's been giving me texts about how she's taking care of it, but the carpet is really bad.
I've been apologizing and not trying to defend myself because it's my natural reaction.
And I don't really know how it is.
I checked the house before I left, and it was all right according to me and my housemate.

All I know is that I did not keep my eyes 100% on the eyes, and since I was not watching the whole time, I can't perfectly determine if the dogs got into the living room.
There was 1 (out of the 3) dogs that would job over the barrier, and every time I would make her get off.
When I told her that, she said that there had to all 3 dogs getting into the living room for so much piss.

I'm confused.
I'm quite convinced that all 3 dogs did not go in, nor there was piss everywhere.
But I'm not 100% sure, nor am I able to see the house because it's so far away.

And I'm not sure what she thinks.
All I know is that she's been described as manipulative by other people.
I've seen her daughter's behaviour and I've always got question about how she's being raised.
I hear her on the phone talking, and gets mad over trivial things.
I've seen an online argument of her calling another person a bitch, getting in fight over another person on Pintrest repinning pictures.

Maybe it's my fault that I went in with the mindset of doing this for the sake of being a good acquaintance (we're certainly not friends).
I gave up my long weekend.
She did not provide any payment, nor transportation, though she did leave me half a carton of eggs.
I got lost there for an hour looking for the place.
She told me that she'd be home in the afternoon, so I decided that I could wait till I got home to eat. Only to find out at 3pm that she changed her mind, so I was freaking starving for the whole day.

And yeah, I got the dogs to listen to me and start learning how to take walks properly (I walk them, not them dragging me).
I showed them when it is time for food, and when it is not.
I sat there the whole day after the dogs got into some burrs. I legitimately sat with the dogs for over 5 hours just pulling burrs out. I was determined to not get the dogs fur to being cut off. (and yes, that was my mistake for taking them for a walk in a forest trail).

And what was she thinking?
She told me to sleep in her room, and she just leaves her underwear lying around the room.
Man, I'm not interested in you. I admit that you are a hot woman, but no....

So right now, my plan is to just do whatever she asks me to.
Pay for whatever she asks, and just get over it.
And that will be all, seriously, if she asks any more of me after I pay her, I'm going to freak out.
And whatever happens.... I don't think I've ever trust this person again.

Maybe I have this notion that I should be able to trust people just because we go to fellowship together, and most of them seem responsible.
But right now I need to take responsibility, and hopefully I can get to the bottom of this.