Extreme anxiety, going back to work

Can you August Mama's who have gone back to work talk me through how you did it? I go back Jan 6 (kindergarten teacher) and I am having extreme anxiety in leaving him and leaving him in someone else's care. My little guy had a rough start to life, a month early, hard and scary labor and a week in NICU. I have been home with him every day, all day since Aug, 30th and I just really don't want to leave him. (In Missouri to break your contract you have to pay money to the district and your certification is on hold for a year.) Every time I think about it I have a panic attack or near one and cannot control the crying. I've noticed lately my anxiety has been way more prevelant, not just with the baby. I do take medication for this, but seriously, how do I go back to my crazy environment at work, manage to pump 3 times, stay sane enough to work with with a bunch of 5 year olds and get through the day without crying, missing my little guy? Any tips, stories, advice, would be greatly appreciated.