AITAH for telling my downstairs neighbors that they can go fuck themselves because my dog barking and shitting inside is ENTIRELY THEIR FAULT??

Came home from work to a note at my door with a threat to call the police if I don't "get my dog to shut up and stop going number two on my doorstep." I immediately recognized the handwriting from another note that was left near the front door a few weeks ago, but I didn't need that clue to know who it was from. Without even entering my own apartment, I dropped off my bag and stormed down the stairs to yell at this woman for her audacity. Reddit, I'm not lying when I say I left her in tears. And you know what? I don't feel bad.

Have you seen those TikToks where people put a treadmill at the top of the stairs at full speed and drop stuff on it so that a bunch of random shit goes flying down the stairs? They're marketed as "oddly satisfying videos," which is so laughably off-base. Well, a few weeks ago, my downstairs neighbors was apparently inspired by these videos and the desire to go "viral" (aka she's an immature dipshit), and decided to do it herself. She left a note (the aforementioned) downstairs explaining that she would be using the stairwell for an hour from 11am the following day, and that she would leave donuts in the foyer as compensation. I work during those hours so I didn't really give a shit, though I did wonder what the hell she was up to. Just for context, I live in a sexplex of single unit apartments, so there's like seven of us in this house.

I came home the following day and the stairs were littered with ribbons, a coke cans and not a few shards of glass. I saw the treadmill at the top of the stairs, and recognized what was going on immediately because my nephew had sent me one of these dumbass videos the other day. I went to the girl's apartment and told her this was unacceptable. She apologized and actually agreed with me, telling me she just wanted to see how the video would do on TikTok and that it flopped heavily. I told her I was sorry to hear that, but that she was going to have to clean the stairs, to which she also agreed.

Reddit, tell me I did not come home the next day to find more shit littered all over the stairs, with a treadmill still at the top!! So I go to her door, and guess who isn't home?

When I'm taking my dog out later that night, I do my best to sweep the debris on the stairs away with my foot. I thought I had cleared a path, but as my dog stepped down, he yelped in pain. I panicked and checked out his paw. He had stepped on a glass shard. The poor guy looked to be so scared, and I can still hear his shrill barks as I took out the shard with tweezers.

After this, my neighbor is nowhere to be found for weeks, never answering the door when I come by. So I just have to deal with the situation on my own. My dog had PTSD from the incident and started refusing to leave my apartment, but his bowels didn't get the memo so he began going to the bathroom in my apartment. Day by day, I have gotten him to go a little further from the apartment, but every time he gets near those stairs he starts howling. Oh, and this entire time the treadmill is still out on top of the stairs which themselves are still a mess! And my neighbor has not been home anytime I've come by!

Eventually I get a very immaturely vindictive but satisfying idea: since my dog won't go outside, why not train it to shit in the doorway of the girl who started all this? And that's exactly what I did. At that point, I figured she had to have been just hiding out from me, so this also served as a way of "laying siege on her." I guess she couldn't take it after three days, because... that was today. Note day.

It felt good to have it out with her, and I finally got to tell her that I expect her to pay for vet expenses or I'm suing her. And I called her a delusional fame-seeker with no talent except making a mess of things. I hit a nerve and I don't feel bad about it, but everyone I told so far has said I should apologize. I'm reasonable enough (and I don't love making people cry) to know I could be "seeing red," so I wanted to make sure via online forum: Am I the asshole?