AITA for not unsaddling my horse after a riding lesson?

My family has been friends with Company X for years. My younger brother is good friends with their son, and my older sister is good friends with their daughter, so it’s always been a family affair.<br><br>Mr. and Mrs. X are aware that my older brother (the brother in question) and I are the only two in the family who are passionate about horses. We’ve grown up with them since we were little, and we even have two at our farm (we’re not rich, contrary to some assumptions, my parents are just very good at saving money and planning ahead) so I guess you could say we’ve kind of grown up around them.<br><br>In fact, Mrs. X has even joked about us one day taking care of her horses as well, and for a while, we did, whenever they were travelling. Which was often. It was no bother, since our farm was literally next door to theirs, and it was only a short walk between the two.<br><br>I switched to a different riding school a while ago, but my older brother has been with the same one his entire life, and has even begun helping out. Some weeks ago, Company X had to go out of town again, and Mrs. X texted my parents, asking if we’d be willing to take care of the horses, or rather, one in particular, since it had recently had an injury. They have three horses in total; two are old, and the other is a stallion that my brother and I have ridden since it was a foal. My brother unsaddled it, and I took care of it since I had more free time (I’m getting my Master’s, which is more independent work, while my brother is in his last year of high school).<br><br>I walked the stallion, gave it treats, and rode it at a slow pace. I made sure the saddle wasn’t chafing it, and I was extra careful about its injury.<br><br>Two days ago, I rode the stallion to my old riding school. I had an appointment with Company X (I’m getting my Master’s in business management, and they’ve agreed to let me do a project on their company). I rode the stallion, let it graze in the paddock, and then proceeded to ride home. When I got home, I got of, hung my bag on the fencepost, and ran inside to the WC. I forgot to unsaddle it in my haste, but my brother was in the garden directly next to the paddock, so he could keep an eye on it.<br><br>When I got back, he was leading it towards the stable, and the saddle was still on it. I didn’t think anything of it, assuming he’d take care of it, but when I told my parents about the meeting with Company X, they asked if I’d taken care of the stallion, and I told them the story.<br><br>Then my brother told them I’d left the saddle on it for over 20 minutes, and my parents kind of blew up at me. They said it was irresponsible of me, and I’d as good as abused it. I tried explaining I hadn’t unsaddled it because my brother could keep an eye on it, but they said it was no excuse.<br><br>Edit: I also just want to add that I’ve had a long day at university and can’t answer every comment. However, I will say I’ve never in my life abused a horse or a human being in my life, I do not abuse alcohol or drugs, and I do not believe I’m above the law. And to those saying I left the animal for six hours, that is entirely on my brother for not keeping track of time, and the entirety of the time spent was with me riding it to my riding school for the meeting, which it was not required to attend. I unsaddled it as soon as we were home. I also realise I wasn’t clear on what paddock it was in, and for that I do apologize, but I did not leave it in a paddock with other horses where it could be injured, I left it in the paddock for a single horse, which was where I left it unsaddled when I first got home. I understand I made a mistake, and the fault of leaving it saddled does lie with me, and again, I apologize for my mistake.<br><br>Edit 2: I thought I’d better clarify how long I actually spent at the riding school (I also want to point out I was NOT at the riding school for six hours. It was from 2pm - 3.15pm. It was supposed to be a 3pm meeting, but they were running a bit ahead of schedule), and I apologize if my story was unclear on what happened at the riding school, or why I decided to ride the stallion there. At the time, I was focused on getting the story down more or less coherently, not on the exact details, and again, for that I apologize. I realise I wasn’t as clear as I could have been, and I should have double checked my story before posting it.