AITAH For breaking up with my boyfriend because he killed my bathroom gecko?

So I 25F was dating Oscar 28M ( fake name) for almost 2 years now and we were talking about moving in together and he started staying over with me regularly. There was a little gecko (I called him onion because he was pealing) in my bathroom when I moved in three years ago I just give him some space and we coexisted just fine, he ate spiders, flies basically every annoying bug.

When Oscar started coming over he noticed onion and said “gross do you want me to kill it?” I told him if he ever touch my little onion that I would break up with him and to just let him be.

Anyway a couple weeks ago Oscar started to move his things because he lease was up soon and I didn’t mind. He work some days from home so sometimes he was over my apartment if his roommates were to loud.

I came home from work on Saturday and Oscar wasn’t home, I didn’t pay attention although he was supposed to stay the weekend I went to take a shower and cleaned the bathroom, when I was changing the bag I noticed something moving and I freaked out I open the bag and found my little onion there without his tail barely moving I was so scare I put him in a shoebox and took him to the vet, the vet said he was too weak and more likely wouldn’t survive, the vet gave him something for the pain and told me I could hold him if I wanted then he died 2 hours later.

I was so sad and he obviously didn’t get in the bin on his own so I called Oscar told him not to bother contacting me again because we were over.

Someone who goes out of his way to harm a little animal who is literally just chilling there can’t be trusted. He new why I dump him and started making excuses, he said it was an accident that he didn’t see onion and step on him (why would he be on the floor) then that he probably got on the bin on his own and died because of lack of oxygen and more lies I don’t even care about.

I change the code of my door and put all his shit outside the door and blocked him everywhere know people I don’t care about are calling me to tell me I’m dramatic and can’t end my relationship over a gross creature, I honestly didn’t care but my mom told my I was exaggerating too and although I won’t get back together with him I want to know if I’m exaggerating or if I’m justify with breaking up with him.

Sorry for the rant and let me know if something doesn’t make sense (English is not my first language)

Edit: I posted a picture ( not the greatest quality I have a shitty phone) of onion If y’all want to see him and yes he has a fly in his mouth because he was a killer machine lol