Oh no my lovely, call your GP now and get signed off sick. I was in exactly the same situation a couple of years ago. I started at a company that was so awful for so many reasons I knew by the end of my first day I'd made a massive mistake.
By the time I'd been there six months I was like a completely different person with the stress of it, it was a field sales job and every single day I was trying to think up ways to make myself die. Looking back now it was like the stress of it - the micromanagement, the constant omnishambles and in particular working with quite a lot of people who were not nice at all had messed with my mind to the point I just couldn't think rationally and was spiralling very fast into a very dark place.
No job is worth feeling like you are feeling. Get signed off, and you can recover, take stock, apply for jobs and start feeling yourself again. My probation was 6 months and just before my probation review I went to the GP and got signed off with stress. I ended up signed off for a couple of months, spent the time recovering and looking for jobs, thankfully found one and handed my notice in first thing on my first day back.
It's only a part time job now and I have to be honest with you it's a struggle financially, but it just covers what I need to pay for (I have had to sacrifice the nice-to-haves) but leaving that job literally cured all those awful thoughts I'd been having and I started to begin to feel like myself again and I feel completely cured now.
If you get signed off you cannot get sacked or dismissed I believe (hopefully someone will correct me if this is wrong?), and it will buy you some time.
Please speak to your GP to get a letter, no job is worth how this is making you feel xx