Hey guys, so I'm having a hard time understanding whether I'm in the wrong here, if someone else could please weigh in because my 10 year friendship is on the line. This is quite long, so bare with me please.

I went away for 5 days, got back yesterday and asked my best friend to look after my two cats while I was away - she looks after dogs as a job and is really quite busy, so I made sure to offer her some money for her time, which she declined.

So I got back last night, after travelling for 10 hours and was desperate for the toilet because they were out of order on the train. I walk in, lift the toilet lid and see dirty litter all over my toilet seat - no drama I thought, maybe she was in a rush? (I use food grade flushable litter.) So I bleached the toilet, did my business and went to wash my hands in the sink, where I found the shitty scoop, not cleaned like I asked.

As I'm running the water, both my cats are desperately trying to drink from the water, so I wonder why are they so thirsty? I check their water bowls, the one on the living room window sill is swimming with flies and the one in the kitchen is over flowing so bad there is a noticeable puddle on the floor. I rinsed both out and noticed a film on the bottom like they haven't been washed? At this point I notice the clean bowls I left out for food changes haven't been used either? So she's just been refilling dirty dishes for 5 days.

Then I notice the empty cans of food on the side, with blood on the sharp edges, next to bags of empty cat litter - I'm upset she didn't bother to put them in the bin but don't think too much of the blood as I assume she nicked herself opening them? Until I go to give my kitten (not a kitten we just call her that) some meat from my pizza and she's eating it strangely? I check her mouth and she has a small, very unserious cut on her tongue, so I go back and check the tins and see they have been licked completely clean.

I wake up this morning and let the cats out on the balcony and notice there is dirty cat litter all over mine and my neighbours doorstep, which must have been caused by her blocking the toilet and having to use the bin chute. I spend 20 minutes sweeping it up. I also spend this morning vacuuming my carpet as she didn't water my plants and the cats knocked them over, so the dry soil spilled all over my carpet - she knew this happened, as she put the plant back but left the mess on the floor to be trodden everywhere by both cats (it's all in their bed now).

I also stupidly left paper instructions on top of my electric oven burner and didn't turn the oven off at the wall, which caused me to become very anxious on holiday when I remembered - I text her asking her to please switch it off, so the cats don't jump up and knock the burner on by accident and burn my house down. She didn't do this, my oven was still on at the wall and the instructions were still on top of the burner.

So I've been very upset, I struggled to sleep last night because I can't understand why she would disrespect my space like that? I spoke to my other friend and asked her if I was over reacting and she said no, she would never leave my house like that. On thinking about it, I realised I wouldn't leave her (friend that watched the cats) house like this either. So I called her...

She said if I didn't like how she left the house or took care of them, I should have paid someone to watch them and employed a cleaner. I reminded her I tried to pay her but she wouldn't take it and said I'm her friend, why would she not clean up after herself? She said she was really busy with work and short on time (she messaged me yesterday about how she was going to a city over to buy hairdye, and sent me pics of her dying her hair with her boyfriend, so she definitely had time) and really went out of her way to help me, for free too, and if I wanted any more than the bare minimum, to ask someone else - I said if I'd have known she was going to be coming and going within 4 minutes (I checked on my door cam, that's how long she was there, 4 mins, 6 mins and 7 mins) I would have asked someone else. She said she doesn't usually take care of cats so didn't think the tins on the side would be a problem. We had a huge argument, she said it's to be expected that the house is a mess after leaving animals for 5 days, I told her I'm not one of her clients, I am her best friend and wouldn't ever leave her house or animals like that, she got snappy with me, said she followed what I wrote on the sheet (she didn't) and now because I was upset, I was causing her to be in a bad mood and be snappy with her children, so I told her to get fucked and put the phone down on her.

I wouldn't mind but I told her on the phone a detailed breakdown of how to take care of them because she has ADHD and struggles to follow written instructions, but I also left a written instruction list too - just the usual, put food down, change water bowls, clean cat litter and wash litter scoop after use, water plants etc. I didn't expect her to do much more because she's incredibly busy and also has her kids with her this week, as it's the holidays. I even said not to worry about vacuuming the tracked litter, as I would sort it what I was back, but she asked me where the vac was just incase 'she was so inclined' as she put it. She would call and sort them every other day as her schedule allowed, because there is two of them so I knew they wouldn't be lonely.

I didn't expect though, for the litter trays to just be thrown into their places and litter to be literally in a pile around them as they weren't close to the wall like they should be. She used a bag of cat litter that lasts 3 weeks, in 5 days, and you could honestly tell, I've never seen anything like it - honestly the mess was shocking, I wish I'd taken pictures.

This is the second time this has happened, she took care of my cats the last time I was away, along with another friend of mine and due to some confusion the cats ended up almost not being seen as much as they should have - I stupidly put this down as a miscommunication though because the issue was sorted and the cats were taken care of in the end, plus the house was left tidy. She mentioned this on the phone, how she's now looked after my cats twice and both times she's been in trouble? Like there wouldn't be any issue if you just did what you said you would do and cleaned up after yourself? I dunno, maybe it's my fault for giving her a second chance?

Now though, I can't shake the feeling that she did me a favour, for free, she DID feed them and DID put some water down and DID change their litter, just to a very sloppy standard, so maybe I shouldn't be so upset?

Am I being ungrateful? Am I the asshole?