RAI - I believe the arrangement you are describing is called "bird nesting". I'm not aware of anyone here recently with that arrangement - but you can google it to read up on it.
BTW- I wouldn't completely rule out the possibility that you might be able to keep OM away from kids. Divorce and child custody are very local. I think in the vast majority of places you wouldn't be able to do anything - but it certainly wouldn't to run it by your lawyer and explore options.
Do your best to let go of this during your son's Bar Mitzvah. It's a bout your son. I know its galling, but OM can only bug you if you let him.
