I don't know what to do.

Ftm here, and I just gave birth to my beautiful baby girl, Perry Nichole. She was born 4/20/16 at 3:09 pm. Everything went relatively smooth up until the 24 hour mark when she was about a day old. I had just laid her down for a cat nap between feedings and I had doses off too. I was hardly asleep for 10 minutes when they came to get her for some tests that newborns have. No problem, except they didn't bring her back. 2 hours later after not knowing anything my nurse comes in and tells me that when she eats or has a pacifier it causes her oxygen levels to drop and she has a heart murmur. I am being discharged tomorrow and we can't take her home with us. I have never felt such pain in my life. This is my first night without her and I feel so broken and empty. I have the option to sit in the NICU with her but they want me to try to stay calm because me crying or being upset distresses her. I have been trying to calm down so I can go back but I can't take this pain. I just want to know what I can do to help. They keep telling me that I've done all I can and that all is left is being a strong mommy. It's so hard especially when I can hardly hold her due to her monitors, feeding tube, and iv in her head. I know I shouldn't worry so much but I genuinely feel like I am dying inside every second I spend without her. I'm sorry for this being so long. I just don't know where else to go.