My wife's divorce attorney had a meeting with my kid's therapist to obtain information to be used in custody/visitation dispute - this was done without my knowledge or consent - is there a violation of HIPAA?

No, I see no violation. You and your wife have equal rights at this point where your "kid" is concerned. She must have signed the consent because the "kid" is a minor.

I'm surprised that your Attorney didn't do the same thing.

No, the wife, unless there is a custody order taking away her rights to know the medical condition.

I see no violaton at all

As long as your wife signed the consent for release of information, as has been said above, there is no violation.