Of course you can't thnk straight! You are exhauseted.
OP I felt like you did with my first tongue tied baby - it was hell, he cried and fed and cried incessantly. I was in a lot of pain and I was all alone. I thought it would be better for him if I wasn't around. Just like you I had PND. Mine wasn't diagnosed and was left untreated and yes, it did get a lot better.
Fast forward four years and I had another tongue tied baby and he was snipped immediately. Feeding was hard but I felt fine, quite elated if nything, and it was only then I realised what had happened first time round and what an utter utter bastard PND is.
Here's what can help:
1/ handing your baby to someone else. Preferably get them to take them for a nice walk whist you rest. You might be too wired to actually sleep but don't worry too much. Rest of any type is essential. You can't think straight when you have had no sleep.
2/ Formula. Really. I am a huge fan of breast feeding, but sometimes it really just work out. Mixed feeding is utterly fabulous and a literal life saver. When DS1 had his tongue tie snipped it was too late for us to EBF and he had to have a massive bottle of formula every day. I used to give it to him at night (before bed and later, a dream feed) and he was a different baby over night. Contented, calm, easy. He slept 7-7 and I could relax. Please please consider this option. If EBF is important to you you can always drop the formula later, your body is amazing and it will adjust.
3/ talking to someone. Anyone! Us. PM me if you like. I've been where you are and I am literally here to tell you it WILL get better.
Your baby needs you. You are his mum. You are his world and rightly so, you are amazing. This is difficult what you are doing, but you WILL get though it and when you do, you will see what an incredible thing it is that you have been doing.
Please take care of yourself Splendide xx