Trigger warning!!!: Mention of suicide and poor mental health

I recently did a major fuck up at work.

I work in a small convenience store and a couple of days ago I accidently sold an age restricted product to an individual who was under 18 (test purchase). The manager literally started his 2 week holiday the same day as we were notified of this and told my supervisors to keep me on "lockdown", for the 2 weeks until he got back. Basically that means I'm not allowed to sell age restricted products to anyone without a supervisor being present. This has already completely fucked up the schedule because basically every other customer buys an age restricted product, so I'm constantly shouting my supervisor over to the till and it means they can barely get any of their jobs done (most shifts are only 1 team member and 1 supervisor on at one time). Because of this, a lot of my coworkers are understandably annoyed with me and it feels like my being in the shop is more of a burden than a help at the moment.

I know after the 2 weeks are up and my manager comes back I'll presumably be taken off lockdown, however I don't even know if I'll still have a job at the end of these 2 weeks anyway, depending on what my manager decides and what the results of the disciplinary proceedings and incident reports are. I've only worked there for three months so it seems to me that I'll probably get fired, despite reassurance from one supervisor that I probably won't. Aside from this, being such a burden on my coworkers is destroying my already fragile mental health and self-esteem and yesterday I narrowly stopped myself from killing myself, mostly with the help of my girlfriend. I don't know whether I'll be able to last these two weeks the way I'm feeling after only 3 days, and I really don't trust myself to be alone right now.

Ultimately, this whole experience has also got me to feeling like maybe retail just isn't the right line of work for me. It just sucks because before all this I was actually quite enjoying my job and the supervisors actually liked me the most out of all the other new team members (supposedly).

So I guess I'm asking, what would you do in my position? Try your best to tough out the next couple of weeks of hatred from coworkers and abhorrent mental health and potentially end up getting fired anyway, or quit the job and end up unemployed and looking for work after only 3 months in a job?

Sorry for the long read. I just really need some advice