What would you do?

Birthday party for our neice. My husbands family all smokes and they all smoke in the house where the party is. That's how he grew up also. His family is big three sisters and brother in laws, dad, mom, step parents literally they all smoke. I didn't grow up around smoking at all and the smell bothers me plus Im pregnant. My question is would you take your kids and go to the party or would you skip it? They always act like its not a big deal and my kids will be fine being around it for one day but I don't feel that way. They always make me feel guilty. So what would you do?