weekend help needed

Okay friends--advice/suggestions/support/help needed.  This weekend DH wants to go apple picking in Wisconsin, which is only an hour away from us.  We used to go when the boys were little, they are now 15 and 17.  I get car sick which no one enjoys.  DH has only two modes--super jokey and sarcastic or sullen.  It costs $20 for each of us and he told the 17 YO he could bring his girlfriend, who I adore, but that's another $20 AND he told everyone we could also stop at the outlets.  Where he thinks all this money is coming from is a mystery to me--he also just bought a car over the weekend and where we had NO car payments for the past 8 months now we have a $323 car payment which is more than we budgeted for.  He set out to stick to a $250 budget but alas there was nothing in that price range (I don't believe him, but too late now).  He has worked about a million hours in the past two days and no end in sight so he is likely to be exhausted by Saturday.  I have worked 11 hours 2 days in a row and have a third day of that tomorrow, so I am pretty much sick of the human race too.  All of this sounds like a recipe for disaster if you ask me.  In all honesty I would rather not go.  I would rather he take the kids and me stay home but we are supposed to be doing more family things.  He and I have virtually nothing to talk about so the car ride is likely to be the oldest and his girlfriend being goofy, the 15 YO being sullen because that is his MO lately and DH being sarcastic and tease-y with everyone.  I hate the weird dynamic between DH and the oldest and nothing I do or say helps--we have discussed it ad nauseam in marriage therapy too and it just isn't getting through.  I wish DH could just have normal conversations/interactions but he can't.  Examples: the oldest and his girlfriend are walking in front of us holding hands--normally mind you--and DH will barge in between them and break their hands apart.  Why??  Or DH will continually bump into the 15 YO on purpose and pretty soon they look like a freaking circus.  Again, why?  I am tired of being looked at everywhere we go--we do not have toddlers any more, we should be able to go places just normally.  So the car ride is an issue for me, the weird interactions between DH and the boys is an issue for me and the money is an issue for me.  Should I opt out and say I have too much school work to do or that I don't want to be car sick?  Another option is to take two cars, which sounds dumb but I can say it's because of my car sickness.  When the 17 YO was in rehab 90 minutes away we took two cars every time we visited not only because I get car sick but because car rides with DH are so unpleasant.  I would rather drive alone.  But how weird does that look to the girlfriend?  Or should I not care what she thinks?  It will make DH's car less crowded if I drive myself and then I don't have to listen to the ridiculousness.  The youngest is likely to drive with me too because he and I listen to books on CD and DH won't.  Thoughts?   Even as I type this I can see I have to be more firm and just put my foot down about some things or this day is going to suck for all of us for different reasons.  I think I will take my own car and say we cannot stop at the outlets because the $100 for apple picking is enough.  Just those two things would make me calmer.  I was actually going to email my doc for a xanax scrip to take with me.  How sad is that--take drugs to make it possible to deal with your family.  Okay--I am rambling--any thoughts or alternate plans would be appreciated.