I have walked that same road and it is hell. I'm so sorry you are enduring this.
It won't last all the years you think it will. The main thing is to be very careful not to be accused of parental alienation, which is a very popular false accusation these days.
My ex accused me of parental alienation because DC didn't want to visit and the judge almost fell for it, saying I have to send them regardless of their wishes . we had a final hearing and I was able to explain that I had tried but it had been detrimental to DC, giving examples, which luckily turned things around and the contact order is centred around what the children are capable of doing. They are front and foremost in all the decision-making.
When they criticise their father, my job isn't to agree that they are right (because, let's face it they are!) - it is to be a listening ear and say things like, "Oh, really? Gosh. That must be difficult/annoying/frustrating". And then move on.
They don't feel undermined or told that their assessment is inaccurate (because it isn't) but they also don't have one parent badmouth in the other, not only is bad for the child even if it's true - because they are after all half of that parent and sometimes no matter how bad that parent has behaved, they're still loved by the Children - but also his dangerous in a court because it can be misconstrued as alienation.
It's so painful to go through this, but I would say that my DC told me, by trying to push them to go when they can't face it, I'm leaving them with nobody in their corner. They needed an adult on their side that way and I explained it to the judge who thankfully understood. But they did have to jump through the hoops of having tried first and that was the worst time ever, for all of us.