My babysitter was exposed to flu...

So my MIL watches my oldest son (2yo) every thursday so that I can go to moms group with my youngest (13wks).

I just found out today that my FIL was diagnosed with influenza A and has been hospitalized due to the fact that he has asthma/copd and since he's sick that means my MIL has been directly exposed. As of this evening she says she doesn't feel sick but would understand if I don't want her to watch my son tomorrow.

I'm torn because I'm worried about any of us getting sick but I also look forward to this moms group each week because it's my "me time"

What would you do???