scout ~ I can't believe he said that! kml has it right on with the gaslighting.
There are a few moments in my sitch in the past year that floor me in the same way. I am grateful that they happen because they are touchstones to remind me why things have to be the way they are.
I also worry a lot about parallel parenting vs. co-parenting and the impact to my kids. I am on almost exactly the same timeline as you, with a similar amount of discord (but not the same details). I badly wish we could co-parent, but it's going to take time. Just a month ago, my X was making outrageous allegations in an attempt to withhold our children from me. So it's going to take some time. I'll never forgive her, but I'm not going to entrench myself with resentment for the rest of my life at the expense of my kids' emotional and mental well-being. It sounds like you are in a similar place.
Sometimes I wonder if my desire to co-parent is just as hopeless as my previous hope to R. Wishful thinking.
But... I will leave the door open. Multiple experts have told me it will likely take a minimum of 12-18 months for some of the discord to subside before we can really start working together. I would be surprised, the way my X behaves, if it will be that soon. I'm open-minded, but I think it's unlikely that we can co-parent effectively in the very short term. I'm guessing it will take you two some time as well.
As part of our parenting agreement, we are supposed to go to co-parenting counseling soon. I'm skeptical that we will make progress given her current mindset (she made absolutely false claims in our last court session, which the experts saw through). I suspect she will try to convince the counselor of her narrative. We also tried co-parenting last year for months, where she blamed every challenge our kids faced on me (rather than the effect of the S, or just normal development). Just throwing out that you might want to consider adding a stipulation in your parenting agreement that you will attend co-parenting counseling together -- I just don't know what timeline.
Anyways, my approach is to have an open mind and open heart. If she comes around and starts taking steps to work together, I am willing, for the sake of my kids. They deserve to have 2 parents working together, and I will own my responsibility to work towards that. It sounds like you have the same mindset.
One thing I did last year that was really fantastic was to take a co-parenting class (by myself, which is how people usually do it). So many of the ideas meshed with DB principles. And the class discussions from real people going through the same process were really enlightening.