Hi there. I'm sorry you are having such a rough time. This happened to several friends of mine. I don't want to frighten you, but for one it did not end well. Because of what happened with her, I take your sort of problem very seriously, as you should, too. If you are having so much anxiety that you cannot sleep, you will need some help taking care of baby if at all possible, until you are able to get help.
I feel that a certain amount of anxiety is normal with postpartum mommy brain, hormones, etc. But in your case (and many moms), it may be to an unhealthy extent. Please don't feel alone. You are not.
I would suggest nursing and sleeping with your baby nearby and in a safe sleep situation. Drink some chamomile tea to help relax. A glass of wine may be okay, but it may keep you up. Take a walk with baby or just get out of the house during the day. Exercise helps, if you can.
This is the most important thing: get to an understanding therapist ASAP. You may require anti-anxiety medication. If a general practitioner or your OB try to write you off with sleeping pills, that will not cut it. Trust me, even if you only need to take something for a short period of time, it may save your life and/or baby's. There is no weakness in accepting help. Please call as soon as you can. Everyone goes through difficult times in life, and for many women, this time is while caring for a newborn. There is no shame in visiting a psychologist or psychiatrist when needed. Please take your feelings seriously and take care of yourself so you can take care of baby.
Hope that helps.
I was like this too. For me, the longer she was in the world, the less anxiety I had. She's two now. She slept beside me, with a nightlight nearby, so I could see her sleeping and breathing whenever I woke in fear, then I could get back to sleep. Does your baby sleep nearby? If you truly cannot sleep, then anti-anxiety meds are probably important, because sleep-deprivation is extremely serious. If you are having desperate and calamitous thoughts, I'd seek help immediately.