Wouldn't a T have stg more interesting to talk about with his/her spouse than clients?
Also they are bound ethically not to...

MKAC, I wouldn't like this one bit. There's no reason what so ever for him to do so- my current T does his billing but those previous that didn't never shared my file with others (at one clinic all Ts met once a week for supervision, where they talk about their clients and stuff- I was told beforehand, asked to sign a permission slip and reassured that no identifying details would be shared).
I'd be very angry about this- given the circumstances even more so- you two know each other, so she could be tempted to read your file more than in other cases.
I'm glad you're taking actions. Honestly for me this would be a deal breaker- but I'm paranoid about my privacy