You know what you do get over this, my daughter was 8 weeks prem weighing only 2lbs 9oz she came home 8 weeks later she actually has a heart condition and was and still is absolutely fine she is now 2 I kept her in our room till she was 6 months old till I could stand no more of the snuffling and grunting in her sleep and decided I needed the sleep.
I only used a normal baby monitor but you can buy then that detects there heart rate like what they use in the prem unit but its not attached to them.
BLISS the premature baby charity these guys are a uk based charity I'm not sure where you are hunn but there's bound to be similar in your country they are an amazing help and support just remember hunn you aren't alone and every mother there ever has been has felt afraid at some point.
Hugs xxxxx