I feel very bad about my history with animals

When I was a little kid, I used to be horrible. Every time I thought an animal was too cute or something, i’d get violent, terribly violent. I regret it so much and wish I never did anything like that. It follows me in my mind and I hate it even though I was a child. Then a year or two ago, I got upset at my cat and tossed her onto the bed very quickly and hard, and pushed her down. I remember feeling like I didn’t want to hurt her but I didn’t want to let go. I cried after it happened and gave her many treats. Around the same time, my dog got me mad i just smacked her nose but I still feel sick to my stomach thinking about it. Idk if i was 14 or 15 at the time? I would never do anything to hurt any animal now, but why did I ever do it back then? It makes me so sick thinking about it and now I can’t STOP thinking about it. I still never wanted to hurt my cat, but she got on my last nerve at that moment and it happened multiple times and I threw her pretty fast. I can’t believe I’d ever do that. I’ve been hating myself for it ever since i started thinking about it again. I can’t forgive myself and Idk what to do. I wish I could go back in time and never do what I did. She was still only about 5 months old at that time. She means the world to me and we have a very close bond, but now I feel like I can’t love her because what I did. I feel like I can’t have friends, or anything really because I feel like I don’t deserve anything. I feel like a terrible monster and I hate that I ever did anything to a little angel that didn’t even do anything wrong. Idk how to forgive myself. I hate that I did that and I wish I never did. It still wasn’t as bad as it was when I was little, but it’s still not okay at all and I can’t go back in time and change it, so now idk what to do with myself. I feel like I don’t deserve to be around my cats babies even though I love them with all my heart. I’m 16 now and not the same ragey person as i used to be. I had a lot of anger built up from an ex that I was with at the time, but still WHY would I take it out on my beautiful cat. The more I think about it, the worst it gets, it’s sucking up all of my happiness.

I’ve said and done so many hurtful things growing up, especially in elementary and middle school. I was very passive aggressive and mean for a majority of my life, and I’ve hurt peoples feelings. I’m no longer like that now, but every single thing I’ve ever done wrong replays in my head constantly, from the moment I wake up to the second I go to sleep. I know I deserve to feel the chronic guilt and shame, so I feel even more guilty pitying myself. It’s eating me alive, I’m so scared. I know people must hate me, and they have every right to. feel like I don’t deserve to have moments of happiness because I’ve taken that ability away from someone before. I’m not diagnosed, but this has been going on for years and I’m scared to talk to anyone about it because I fear they would look at me differently knowing I’ve hurt someone’s feelings. I feel like a monster. It’s ruining my life and I don’t know what to do.

my cat was smelling my other cat's bottom so to get him away i like quick "slapped" with the dorsal of the hand on his face and i got afraid that i did too hard so i compulsively did it again with similar strenght that i used to check if he was hurt and i regret it, like it wasn't a hard slap meant to hurt, but i did that impulsively and maybe i exceeded a bit over the limit in which it doesn't hurt. like he definetely reacted but i don't know if he was hurt, like he reacted in the moment but nothiny else, and he's lovey dovey. i dont think he was hurt but i feel bad. because if i did it once as a mistake i shouldn't have done the same thing again. i feel like an abuser. there are many things that are happening to me and im getting overwhelmed and i dont know how much longer i can hold on. because one thing i can't do is to forgive myself over mistakes.