Road Trip..... from hell??

Leaving Thursday to drive up to Fort Worth with a full van. Not only will I have my two year old daughter with me, but I will also have a 3 year old boy and a less-than-one year old (I can't remember how old he is). Plus their mom, a woman I don't really know all that well, but is nice. See, my husband and her husband work together and they are both in Fort Worth for work right now so apparenlty we had both planned on driving up so our husbands thought we should do it together. Now, I've tried to get out of it numerous ways, but apparently my husband does not understand that I really don't want to take a 5-6 hour road trip with 3 young children. One newly potty trained and probably having to pee every 10 minutes. The other still at least partially breastfed which means additional stops at feeding time. Now my daughter, she has always been a trooper on car trips. She can easily go 2 hours without stopping (usually sleeping half of it or more) and since she is still wearing diapers I don't have to listen to "I have to go potty" 10 minutes after having passed a rest stop.
Oh, one more thing - since my husband drove himself and this other guy up to Fort Worth and I am driving everyone else in my van, anywhere that we go while there will have to be in two separate cars. We planned a trip to the Dallas zoo, so now they are going with us, but the husbands will have to drive separately. We planned to go out to a nice dinner one night. So now we will all have to go together, with our husbands driving separately. Does anyone else wonder what the point is of driving all this way so I can spend all of my freaking time with this other woman and her children? The whole point was supposed to be that we could spend the weekend together since he's gone so flippin' often nowadays. But instead of going Friday-Monday, now we have to go Thursday-Sunday because the 3 year old has a dr appointment Monday morning. So essentially we're driving all this way to really only have one full day together (Saturday) and that is now going to be spent with this other family at the zoo.
I'm a very private, solitary person. I like to be by myself, with my family, and sometimes friends who I know well. I don't like to be around people I barely know. I'm not comfortable. I'm very bitter that what I was thinking of as a vacation has turned into a chore.