No such thing as Co Parenting with BM
Co Parenting with BM is absolutely impossible. If he were to say black she would say white. They have been divorced for 10+ years. The divorce was a bitter horrible ordeal drug out for way too long.
The first year was rough but since then, there is no co parenting at all. It is all parallel. The only communication is via email/text regarding pick up/drop off day/times (DH is long distance).
There have been a lot of instances when DH would have like to have addressed things with her, but swallowed and did not as engaging with her never ends well and to be honest I think the life was sucked out of him during the divorce and the 1st year following.
It is such ashame with people that pro create together end up so bitter (her) damaged (him) that these kids have no idea what a healthy relationship looks like and that all divorce doesn't have to be so ugly.