OP, as said before, newborn babies is an incredibly hard stage, sleep deprivation is so tough, I remember it well, I once brushed my teeth with moisturiser instead of toothpaste I was that tired! It didn’t taste nice, but my teeth & mouth was smooth!
I’m sorry I only read the first pages of the thread & skipped through the rest, Did you go the gp? I hope you’ve managed to get some form of help, going through this alone must be hard on you. I did it with my husband and my parents & I still found it tough.
Meanwhile if you get any offers of help in RL, from friends take it, even if it’s just them popping round to watch baby while you sleep, don’t worry about anything else, ask them to make YOU a cuppa & a sandwich, it makes all the difference, equally, ask for help, it’s okay to ask.
It may have been mentioned already but does your baby have a dummy? I only ask as with my firstborn, we decided not to give her one, on the advice of my mum and my baby cried a lot. So when I had my 2nd, I knew straight away I was going to give him a dummy, it so much easier & calmer for us 2nd time and that’s what it’s about, making life easier for yourself & baby. Just a thought.