I had twins 9 1/2 weeks early, born after an emergency c-section for a placental abruption. They were born fairly big for thier age (3.5 and 4 lbs.) but still had a whole variety of premie illnesses and spent 29 and 32 days in the NICU. Ian had breathing problems and Evie had a PDA, breathing difficulty and contracted staph while in the hospital so she had to be quarantined. I can totally relate to the helplessness, guilt and frustration. But now they are 3 1/2 and doing very well.
I think for me the hardest part after my general fear for the babies was how to be super mom. I had two kids at home (5 and 1) who needed my attention and my husband had to go back to work or we had no income, trying to pump milk, plus recovering from the c-section and being at the hospital all the time. It was overwheling and it took me a while to figure out that I wasn't supposed to do it all, that there were friends and family who wanted to help and it was OK to let them- especially when I needed a moment for me, just a shower or a quiet cup of tea. That, and it was OK to lose it evey once in a while and just cry because when I didn't I felt pent up. Letting it out made me feel temporarily renewed.
I am so sorry you are going through this. Keep your faith that your beautiful baby will be home with you soon. I wish all the best to you and your family.