I knew I was going to deliver early, but I just didn't know how early. I was hoping my MFM would put me on bed rest at 20 weeks but she didn't. For me, keeping my mind occupied was key. I understand that there's a good chance you might have a preemie so I think you'd be wise to have a plan in place for your other child, have a bag packed (I didn't so I threw some stuff in last minute and had to send other people to get what I needed). However, once you have your plan in place, you've toured the NICU near you, as much as you can, put it out of your mind. If you're working, adjust your work as much as you can. I worked from home in the recliner for a couple months since most of my work was on the computer and the phone. If you aren't working, try to take up some hobbies to keep your mind busy! Lots of women I know learned how to crochet or when pregnant and made some really amazing gifts for their childs! One woman called hers a "prayer blanket" because with each stitch, she prayed for her unborn child!
Wishing you all the best on this journey! I have 29 weekers who are doing amazing now so don't think having a preemie is a terrible thing. It sucks, but it's not all in vein!