How to get out of going to wedding?

Friends of my husbands and I are getting married this Saturday. My husband is a groomsman. I RSVP that we would both be going but being that we live in a small town and everyone we know and trust to watch our kids is going to the wedding (I dont have any family here and my parents in law are going to even though they don't really know the couple but were invited for some reason), we weren't able to find child care for our kids, 2 years old and 10 years old. My husband called the groom and he said we could bring the kids but I dont feel comfortable with doing that. My 10 year old would be ok and probably have a good time but my 2 year old will make it miserable for me since I know he wont sit still and be quite for the ceremony and Ill be running all over with him at the recpetion (Im 6 months pregnant to boot). I've been trying to talk to my husband about this but he keeps insisting I go, even trying to guilt me into going.