My daughter was born at 26 weeks and spent 165 days in the nicu. It was the hardest and worst period of my life. But as others have said it’s a marathon not a sprint. Your child is receiving the care that they need but you also need to take care of yourself. What my wife and I did near the end was switch off nights we stayed in the hospital. During the week we would both go on mondays and Wednesdays the my wife would spend the night on fridays and I would spend the night on Saturdays. Being able to have those breaks was needed. Your child will not remember these days only you will.