Wicked Co-Worker

Sidney
I am one of only two female employees at a completely male dominant dealership. The other woman is married with two kids. I am having a high risk pregnancy (which she knows, unfortunately) for a few reasons and after a few missed miscarriages I'm finally 12 weeks 4 days and everything is looking great as of my last appointment. 
So, my fiancé and I bought a travel system. We are very excited to have good, healthy news-- for this is the farthest we've made it. Well this other female co-worker of mine always comes up from the back where she works, peers over my shoulder as I'm working at my front desk, and reads what I'm writing, typing or looking at. Well, Chris and I were messaging back and forth about  the travel system and I had sent him "purchased ☺️💗💙 (with an attached photo" a simple milestone celebration for the two of us. 
This co-worker of mine just blurts out "I wouldn't have bought that yet. Especially since you're high risk... you don't know what is going to happen. Just sayin'." Which is her thing... it irritates the hell out of me... "just sayin..." 
I struggle with trying not to be this constant cauldron of boiling anxiety all the time. It's not healthy and it's emotionally taxing. But after my last appointment I was feeling pretty confident and had managed to calm down. But what she said sent me into a tailspin... my only thoughts were: "well, I am feeling fine right now, what if something is wrong?" And "my bump goes away when I lay on my back... maybe something IS wrong?" Or "I kinda tripped today when I walked back from the service drive, maybe they hurt the baby?" These are all things that I know are normal for this time in my pregnancy, but I couldn't help but be irrational all over again. 
She does this frequently an gets some sort of sick satisfaction from making me feel little and putting me down. I'm very frustrated with her. I hate to say that comment ruined my day, but it kinda ruined my day. What the hell do I do about her?