Agreed, great answer. As a fellow parent, I know that connection with your kid is far more important than whatever “dignity” you’ll “lose” from going on the trip.
He’s probably old enough (only you know, OP) for you to even talk about your discomfort with going, and to be open about your personal pros+cons of going. Who knows what he’ll say, but it sounds like a good conversation to have.
I’m in my 40s… similar to you, used to eat fast food often, and enjoyed it. I was having a horrible day a couple weeks ago, and thought “fuck it… I’m eating at McDs.” It was disgusting, not like I remembered it all.