WIBTAH if I broke up with my girlfriend over my dog?

I (19m) have been together with my girlfriend (19f) since we were like 12. For my 10th birthday I got a dog, he is called Charlie and also is the last thing I have that my brother gave me (he died from pancreatic cancer two years ago).

So me and my girlfriend got in a fight earlier. She is someone who likes to go out and party while I prefer to sit at home and read or watch some movies, maybe go to the gym, stuff like that. Now, yesterday she told me that she had an and I quote „family emergency“ and wouldn’t be able to come over until the next day. Well today in the morning I got a call from someone in our friend group who asked if my gf got home safe. I didn’t know what he was talking about and now it turns out that my friend group was out partying and there never was an emergency.

According to my friend my gf told everyone I’m not feeling well which is why I’m staying home. After that I called my gf’s phone multiple times but she didn’t pick up. Instead she turned up at my place about an hour later. She looked horrible, really tired, exhausted and her hair and make up was a mess. I asked her what was going on and why she lied to me and all of that spiraled to her calling me insecure, which made me accuse her of maybe doing something with some guy at the party (not my proudest moment), which again led to a screaming match between us. Said screaming made my dog go anxious and he barked at my gf, who in turn kicked him to the side. After that I immediately told her to leave and she did and since then has written me countless apology texts.

After that was over I checked on Charlie who seemed to be fine but to be safe I drove over to a friends house whose dad is a doctor for animals. But unfortunately neither him nor his parents were home, only my friends elder sister. She is super sweet and has been like a mature older sister for me and the friend group for a long time so after she asked what I was doing there I told her everything. She immediately let me in, cooked for me, looked after Charlie and all in all spoiled me and Charlie way to much.

Now I’m sitting on her couch and am looking at the apology texts from my gf coming in, but I kind of don’t care about her feelings anymore. So basically my question is if I am justified to break up with her and throw away such a long relationship because of something like this, since I kind of want to.

My friends sis who I’m staying with till he and his parents get back told me I’m an idiot for even asking but I’d still like some unbiased opinions since she is very overprotective of me in many ways and I have to admit coddles me a bit to much when it comes to stuff like this. She already told me to break up with my gf about way smaller things so I’m not sure how much I can trust her opinion on this.