My Gf (18F) can’t apologize at all, it’s driving me (19M) crazy

First of all english is not my mother language, so forgive me for any mistakes i make.
I’ve been going out with this girl for more than a year, and the thing is she can’t apologize even if her life depends on it.

Let me elaborate, she’s a very hurt girl, many traumas because of her shitty family. She has cronic anxiety and anxiety attacks too. I knew that but i still fell for her and so we started dating, i myself i’m also a very traumatized guy, shitty family too. I’m very cold and i put reason before feelings very frequently, however i’ve always tried to be very open with my feelings with her because i really love her. However she has many faults like all human beings, she puts feelings before reason always and like i said, can’t apologize at all. Whenever she fucks up she tries to shift the blame to any other thing, and if she fucks up with me she always tries to bring out anything i made during our argument to try and feel not so guilty, usually she says i raised my voice at her or that i treated her harsh (i never call her words). I can’t stand that, i know perfectly that she’s just trying to not make herself the only one at fault. The usual only way for our arguments to end is if i apologize or we leave it on medium ground unresolved.

The thing is yesterday we went to eat together and there was a student discount, we’re both students but i didn’t had my student card a the time, so i asked her if she could pay with her card so that the discount could apply for the both of us and i’ll give her the money through Bizum. But she didn’t want to because she had very little money on her card and she was going to pay in cash because spending money on her card gave her anxiety (don’t read too hard into this, she just hyperfixated on that got stubborn), but if she paid in cash the discount would not apply (we’re students so we don’t have many money, all that we can save it’s worth it). I insist her but she wasn’t going to change of opinion, so i got mad and i called out the stupidity of her reason because if she paid with her card she’ll still have the same money plus the one we saved thanks to the disccount, but there was no convincing her. So i got so mad that i lost my appetite and told her that, she agreed and after 5 minutes i complained that she was being unreasonable, and then she started saying that i raised my voice at her and talked to her harsh. I got even madder because not only she was being egotistical she was trying to tell me i had to apologize for raising my voice at her.

We got into an argument, a very strong one and i couldn’t take it anymore so i went for a walk and leaved her alone. She then came to search me to keep saying i treated her wrong and that i should apologize, so i decided to go home and ignore her for the night, she didn’t message me either. So the next morning i write her in class to tell her we need to talk about tonight, but she still expected for me to apologize, we continue to argue through text and it’s not advancing.

I know i could just apologize and it’ll all come back to normal, but that’s what i always do and i really don’t think i did anything wrong (believe me i didn’t raised my voice at her), what should i do? Because i’m starting to thing maybe i got myself into a toxic relationship, but don’t really have anyone talk to about this. Help.