Your husband is a grown man and I don't think you should blame the so-called "therapist" for his actions. I don't know why you said you were leaving in September and then didn't go but it doesn't sound like this can get "fixed" the way things are now (either with his actions or your snooping through his things and finding such negative/damaging evidence of his lying) and I would encourage you to leave if you can, now that he's working.