GF(19) is angry that I failed the final she made me take for her

Hi,

My GF is a biology major but took a computer science class though it's not part of her requirements. Naturally, when she asked if I'm willing to help her when she needs, I said yes. However, a few days in, she was struggling and “gave up.” So, from then on, I ended up taking her 2 midterms, and her final, which was yesterday. On the day I saw the syllabus months ago, I told her I haven't learned the material on her final (it's different from my school) and warned her about this. I once again warned her about a potential lower grade than the last two midterms I took for her (I got 98% and 96%). Fast forward to today, I got a D on her ridiculously difficult final. Despite the average being an F, and the fact that I did the math and she still will get an A in the class, she's extremely angry with me and said “if I somehow get a B we're done”.

Her reasoning is that I don't prioritize her enough, which we've been arguing over for months. This stems from a late-night conversation where I said that she is a 7/10 priority compared to my studies which I rate at a 9/10. This is because I am at an academically competitive university where I obviously need to devote time and effort to my studies, and I hoped she would understand this. Yet a few months ago, I would stay up every day until 4 AM helping her write her college transfer application essays, as well as get her computer science midterms done for her. My friends also noted that most of the time they saw me, I was texting and calling her as well.

GF also believes that for the final exam, I had “months to study for it.” This is true, but she made this about me not prioritizing her enough. Despite many attempts to reason with her that I didn't know the material and that she should've done it herself, she doesn't see where I'm coming from.

I would also like to note that she insists on keeping an ex that cheated on her as a friend, though that ex clearly wants to be friends with benefits with her. She sort of threatened me with the exams that if I couldn't get them done for her, she would ask the ex to do them for her. For months I have been trying to get this guy out of her life but to no avail.

So my question is: do I attempt to further reason or just leave? Weighing our relationship over a grade is ridiculously shallow IMO

Thanks!