Today he reminded me of a speeding ticket I got a year ago (got it passing a massive truck with stuff flying off it and hitting my windshield - only speeding ticket I had ever gotten in my life!), in response to my telling him to "drive safe".
Several years before we were divorced, I ran out of gas - just didn't want to take the time to put gas in the tank so I gambled and lost - no big deal but to my wife it proved I was "irresponsible". She brought this up repeatedly during our divorce, as if it proved something, and as if she had never made a dumb mistake. Everybody, including her own attorney, listened politely each time she brought it up, and then moved on to relevant stuff, and I'm sure her attorney told her, "That is not relevant so don't bring it up again.", but it didn't work. Seemed very important to her to prove that I wasn't perfect... .
I think there are two strategies for communicating with an ex which seem to work.
One is for when the kids are much older, like mine, now 16 and older. I mostly communicate with the kids, not their mom, and it puts some burden on them, but usually works out well. My relationship is with them, not her, and they have relationships with her, so if they need to say, "That sounds fine but I want to talk to Mom first to make sure she doesn't have something planned for that day.", they learn to say that, and work things out with both their parents.
But that's not where you are now, for several more years.
For you I would suggest communicating much, much less, and only by e-mail. Only practical matters related to the kids. No emotions and no discussion of the past or the distant future.
Stuff like, "I will drop S2 off at noon Saturday."; "S2 has a slight temperature so when I drop him off I'll give you the Benadryl - 1 teaspoon every four hours."; etc.
You would like to know more about how the child does when he is with his dad, but you probably need to get over that. If you find out that your ex is withholding important information, like medical issues, you should take strong action, like a strongly-worded e-mail to your ex, or maybe even consult a lawyer to hold firm to that boundary: both parents should communicate medical information. But don't generally expect a detailed update about how the child is doing, the way you might expect from a friend who watches him for you. Just accept that you won't get that.
The passive-aggressive stuff can be dealt with by using only e-mail, and responding only to what is appropriate. No face-to-face or phone discussion except in emergencies. If an e-mail has one relevant sentence and then a bunch of baloney, ignore the baloney and respond to the appropriate stuff only.
If your ex has BPD or something similar, and if he isn't getting the right treatment, his behavior is not going to change. But you can establish more distance from him so you don't have to listen to all that stuff.
