I saw your reply to another thread on the legal board. It sounds like you've both enacted clear boundaries, including keeping communication short and emotionless (what we call
around here BIFF: Brief, Informative, Friendly, Firm). I sometimes drop the first Friday in my case

As frustrating as it is, you seem to have the overall plan under control (parallel parenting, a communication tool to document), notwithstanding her decision to go for joint custody
You say the boys have been doing better with less contact and being in therapy. I imagine something like "no interrogating the kids about what goes on in the other home" might be in the custody order, but that's hard to enforce. In what ways are you and your fiancé working with the kids to help them deal with this? Does reach react differently depending upon age and personality?