My job asked for my notice, what do I do if they ask me to stay now?

I’m starting graduate school and would have a hard time working full time at the same time. Classes are online and asynchronous but full-time nonetheless, I asked my direct supervisor if there were any options we could explore to make things more manageable with this change. I really just wanted to figure out an easier way to do both, I like my job, its secretarial work and not a busy office. My direct supervisor pitched some possible options and said they had to speak with higher management about them too. After a week and a half of my direct supervisor telling me they would get back to me later (there were some legitimate reasons to postpone for part of this time) I got a call and they said any options we discussed can’t happen and I was asked to provide my notice. There weren’t any other offers or negotiations, the tone seemed pretty decisive but not hostile. Up to that phone call, any communications after my initial email about going to university and asking to explore more manageable options were verbal.

I was shocked and sad but turned in the resignation as asked via email (communication at this point is all in writing); my direct supervisor continued to ask about/state I was leaving because I couldn’t fulfill my contractual obligations (40 hrs a week worked), I said that wasn’t necessarily the case. It’d just be really difficult and thats why I opened up the conversation to begin with. Despite my clarification I still received a formal notice from higher up the command chain that my resignation was accepted; it also said I was leaving because I said I couldnt meet my contractual obligations. This was so confusing because I was literally told to resign.

I stated once again, directly to higher management this time (2nd time in writing not including my mention of this in my actual resignation letter), that wasn’t true and that there seems to be a miscommunication. Now my direct supervisor and my supervisors supervisor want to have a meeting. I’m really concerned and off put by how this whole situation has been handled and I’m not sure what to do if they ask me to stay now. How do I know they’re being honest if they offer it? Should I stay if it’s offered or hold to my resignation then just focus on my education? What do I do if they keep saying I said I couldnt fulfill my obligations when that’s untrue? I’m confused and anxious about whole thing

EDIT: I did state multiple times that I intended to stay with the company. I do like it here, I never intended to resign and I even told them I’d be understanding if they just needed someone full-time.