I used to hit my dog

Ok so... I just wanted to find help because I'm on my floor nearly in tears. This happens a lot, I just go back down memory lane and remember the stuff I used to do to my dogs when I was younger. I am a teenager now, but I used to abuse my dogs whenever I was like 6-11. I didn't really even know I was abusing them, I knew it was wrong, but whenever my dogs wouldn't listen to me I'd fly into a literal fit of rage, hitting them, beating them, choking them, all this crazy stuff. On walks when they'd bark or pull, I'd lift them onto their hind legs with the leash, which would choke them. I look back on it and I feel awful, like, if I could change one thing in my life it would be that. I love animals so much and I loved dogs but I would just get so angry at them and abuse them and I DON'T KNOW WHY. Like seriously, I can't figure it out. Occasionally, now that I'm older, I'll find myself sometimes raising my voice at one of my dogs and maybe giving him or her a slap on the rump, but I don't beat them anymore.

Why did I do that as a kid? I was never abused, I had a great life and I still do... I have a huge heart and I'm even a vegetarian because I love animals so much but I just seriously hate my dogs sometimes. A few years ago I was diagnosed with ADHD and OCD and panic disorder but idk if that has something to do with it

Please help, I feel like a horrid rotten human being and I know that I am for doing this, I just want to die sometimes because I think back on it. why did I do this as a kid? how can I forgive myself, and how can I get rid of my anger once and for all? I've seen a therapist, but she was no help. I'm just really really sad and upset and feel horrid right now.