Mustardseed: as a teacher myself, I can relate to how stressful our job can be-- mentally, physically and emotionally exhausting.
You may want to read some of the recent advice I got from labug, urWorthy, Maybell and mozza... or perhaps my earliest thread with awesome insight from 25 years.
The stuff with the OW and playdates sounds pretty controlling. I would not expect my H to consult me on every activity or playdate he arranges. I would certainly hope that he would give me a heads up before introducing my D to a girlfriend, but I can't control what he does.
please do not contact the OW anymore. Focus on you, on GAL, on managing your anxiety and stress (which makes everything in a special needs classroom so much worse!)... and work on detaching.
Nothing you say at this point will change how either of them feel.
You can do this-- all of it. If you want to get some feedback on teaching stuff, I'm sure I'm not the only one here, and I'd be more than happy to offer support.