You can't make people like you under the best of circumstances, and you certainly can't make them like you while you're actively badgering them on what you perceive to be their failures of conscience.

Being highly invested and preoccupied by an emotionally consuming mission tends to steal resources from other aspects of your emotional life.

Plan your own vacations when you want to, and plan a suitable combined vacation with this other family when you want to. If they freak out at your planning your own vacations as you see fit, then let them. Bowing to unreasonable demands because someone will make you pay emotionally if you don't is not a healthy option.

Your parents' views are, by current standards, out there. Getting in their faces about it would be needlessly disrespectful, but there's no reason for you to tiptoe through their delusional little terrarium as if you can't bend even one blade of grass.

The most reliable ways to make oneself miserable are attempting to change people and not attempting to change circumstances.

It's hard to send your baby off on a plane without you, though that's less reasonable, because sending him off in a car is statistically a bigger risk.

Separation is where you see if it works better with the adults in two different homes.