Advice on HFM and family gathering

So basically my sister in laws little boy has hand foot and mouth. We canceled Christmas with my husbands side because he wasn’t feeling well and they didn’t want to spread it. Since then she has decided she wants us all to get together next weekend to celebrate. My thing is, from what I have researched children and adults who have HFM are obviously the most contagious within the first week but can still shed and spread HFM for 1-3 weeks even after symptoms go away. Since finding this out I have decided I don’t want to attend the gathering because I have a 3 year old and I am also almost 36 weeks pregnant and that is THE LAST THING I wanna have to deal with right now. Am I wrong for this because she is making me feel like I am the biggest bitch because I said we wouldn’t be going. My husband agrees and is on my side but she tells me I am wrong and what I have researched isn’t true .. I also had no idea what group to post this in