Am I in the wrong for washing my dog in our family shower? My sister thinks so.

Hi, it feels excessive to write about this, but I need others' points of view on this. Sorry if it's a long post.

I (41F), my husband (47M), our chihuahua mutt, and our 6-month-old baby arrived two days ago to stay with my family for the holidays; they live in the countryside with their dog. I have a younger sister (34F) visiting as well with her boyfriend and her cat. My parents have a two-story big house where we both grew up. It has two bathrooms with two showers, one small on the ground floor where my mom and dad shower, and a walk-in, bigger one upstairs by our bedrooms, where the rest of us are used to showering. There's also a room by the garage, detached from the house, where sometimes, after working in the garden, my dad showers. I know, a lot of shower talking!

This morning, while our small dog was with my husband by the backyard field, he came back dirty and stinky; this never happened before; he's generally very clean. We suspect he rubbed himself in some wild boar marking/poop; it had a musky smell. When this happened, I was dealing with our baby while resting in bed, as I'm suffering from heavy back pain since some complications related to giving birth.

My husband, with the help of my mom, tried to clean the dog with some dry shampoo and heavy brushing. The dog was clean of the poop but still stinky. So they came to me. We decided to bring him to a groomer; we left my baby with my mom and went directly to the shop. It's holiday season, so we found the groomer closed. We then decided to go get some stronger shampoo in a store. I was hoping my husband would have handled this issue, but he suggested we do the cleaning together, feeling the dog would have run away (we're not used to cleaning him in the house; we normally bring him to a groomer to avoid messing with it in our small apartment).

When we came back with the shampoo, my mom offered the option to wash the dog in the laundry sink, but looking at the faucet, it felt hard to get a proper cleaning using it. At first I thought of using my parents' shower, close to us on the ground floor, but since it's small, it would have felt difficult to bend in it, especially for the two of us.

I decided to go upstairs to our shower, and immediately understood it would have been impossible to clean the dog together, even if bigger. As I had to shower myself, I offered to clean him, as I would have gotten wet anyway. So I did, then I passed the dog to my husband, who rubbed him with a towel and brought him outside to dry.

Finally I showered, feeling the back pain from the effort of bending. After, as usual, I cleaned the shower floor of all the hair I normally lose and, of course, our dog's. I collected the hair from the filter, noticing that it was fuller than expected, which means my sister didn't clean it previously. This is a regular thing that happens when we're staying in the house together. Sometimes I forget it as well; most of the time she does. I've been considering whether to tell her or not this time, as sometimes it can be a reason for starting a catfight, and yesterday we had one for another misunderstanding. Since we'll stay here for a while, I concluded it was better to bring it up. At lunch I mentioned it, starting the conversation by saying: I don't want you to get attacked by this, but I cleaned the shower filter, and it was pretty full. Did you maybe forget to clean it? She quickly dismissed the issue, saying she was sorry and remarking that she cleaned the bathroom before we arrived, but forgot about it. Her chill reply was reassuring, although the bathroom didn't look very clean when we arrived (and didn't bother me at all).

After this, she said: did I understand right, and did you clean the dog in our shared shower? To this, hearing her aggravated tone, I said with a sense of annoyance: yes, I did. She started asking why I did that, that it was gross since he was dirty with poop. I told her he really wasn't anymore, just stinky, and that I didn't know where else to do it. She suggested doing it with the sink, and I said it would have been difficult to clean him properly. Then she said to do it with the hose outside. I didn't think about it, and to be honest, I think it's too much of a big deal to clean a small dog like ours. She also said that there was a shower by the garage. To this, again I have an annoyed tone at this time, because to me it felt like she was annoyed by something pointless. I told her I honestly didn't think about it. I was more concerned about solving the issue quickly, as I was in between handling the baby and other stuff that was happening at the same time (a package that had to be returned by a carrier that arrived earlier than expected, my mom having forgotten a delivery that was being sent somewhere else where maybe I had to go right away). I told her that I'm sorry, that the dog was already dry cleaned, and that I didn't think it would have been a problem.

To this, my sister got even more annoyed, saying that she has the right to express her dissent, that I should have asked her. I told her I didn't think I had to ask her, because I didn't think it was a problem, that sometimes we had to wash the dog in our shower, and that I didn't imagine it would have been a bother. She kept talking, saying that she doesn't care if we decide to do it in our shower, but this is a shared space and that she felt grossed out. I told her that it won't happen again, but at this point I am super annoyed. I told her I already did it; what else can I do? And she continues saying that she has the right to say she's against it. To this, I am like, okay, but this is enough; we can't go back, and I, to be honest, it's not that I was enjoying myself while doing it.

I left the table to decompress in another room because she was driving me crazy. Am I in the wrong here? Is it really so terrible to clean a small dog in a shower where we use soap to literally clean ourselves and him? Is it so gross, as he's basically getting clean? My mom didn't tell me anything when I said I was doing it in the shower; she didn't seem annoyed by the idea.

I didn't imagine this would have been a problem for my sister. She has a cat that literally, the other day, vomited everywhere on the floor. That has long hair and goes around with its poop attached to it, sometimes sitting on her bed. On the other hand, of course it's a problem for her; she's the same person who didn't want a friend of mine to be sleeping in her bed when they were visiting me at my family's house, and my sister was away. Of course, with clean sheets. But she insisted so much to not want it because it was HER bed and she didn't want someone else to sleep in it that we didn't.

After I decompressed, she wanted to tell me she was sorry if I got upset, and I told her I didn't want to talk. I know I have to deal with this person, but I don't know how.