Need some advice, please?

I co-teach with another teacher (Teacher A). We were put in a classroom together because she took off the first part of this year for maternity leave and I was supposed to take off the latter part of the year for maternity leave. However, I miscarried, so that won't be happening, but classes were set and things just stayed the same. Anyway, this is Teacher A's 3rd week back. Another teacher (Teacher B) had her baby within a day of Teacher A and came back from maternity leave 2 weeks ago. I have been TTC for almost 6 years, and like I said, finally got pregnant this year and miscarried in September. Both Teacher A and Teacher B are well aware of this.

Long story short, Teacher B comes into our classroom EVERY SINGLE FREAKIN' DAY and wants to talk babies to Teacher A...at least once a day, often 3-4 times a day. She walks in, doesn't even look at me or even acknowledge my presence, turns her back to me and goes on and on about babies, asking Teacher A if her baby is doing this or that, or has hit this milestone and going on about how "hard it is to leave my sweet boy over in the daycare all day" (The daycare is on our school's campus). This woman KNOWS I recently had a miscarriage and knows I've been trying for longer than she's even been married. She also knows I'm sensitive and still very saddened over my miscarriage. Is she just a clueless clod? An idiot? Or a b*tch? I can't figure it out. Perhaps the miscarriage isn't fresh in her heart and mind but it is in mine and I'm so angry that she comes into MY classroom and makes ME feel uncomfortable to the point I feel like I have to leave so I don't cry. She comes in during planning period or before or after school most of the time...occasionally during classroom time, but not often. What do I say? How do I handle this situation? I do still have to work with this woman. .