I completely understand your situation. My step-MIL and FIL were very controlling; they moved to Florida years ago & kept bugging us to let the kids fly down alone.The kids weren't comfortable with flying alone, nor were my DH and I ready to let them. DH & I offered to fly with them, but SMIL said she wanted just the kids to visit?! We weren't having any problems with them at that point

, so it was just them wanting to win the argument

. We offered to fly with the kids, drop them off & then do our own thing, but even that wasn't enough! My SMIL actually would berate the kids on the phone, telling them to "talk us into it", "keep bugging us", etc. It finally erupted, I told the in-laws enough was enough and to let it go, and DFIL sent us an email saying they no longer wished to have any contact with us or the kids. That was almost 4 years ago now. We are still amazed that they could severe what was a good relationship over something so trivial. We have made a few attempts at reconnecting, with no success. We are done. The kids, who once loved them, have no interest in them now. They have missed so many milestones in the kid's lives, that it seems almost impossible to forgive/move forward at this point

.
I wish you luck, I hope your situation doesn't turn into what we experienced.