Separation anxiety :'(

Tonight has been the first night I leave my now 4 months old daughter sleeping in her room on her crib. I'm trying to keep it together and not cry but I have a knot in my throat and my stomach... my hubby doesn't understand the way I feel and I hate to cry in front of him especially because it's suppose to be a good thing that she can sleep alone... but I hate it, I just want to have her beside me and hold her... I hate this feeling, is like I'm going crazy... I hope I'm not the only mommy that's gone through this :-(