Oh dear....
I did something a bit like this many years ago, in a work situation. Got an email from one of the really important (overseas) department heads about something. Sent an email to my boss, so I thought, basically saying "I can't believe the head of X doesn't know about this. What are they doing in X office?" but of course, sent it to the important department head.
Three minutes later he rang up, very angry.
Somehow, I pulled from the bag, "Oh no. Did I hit send? I meant to hit save. I was in the middle of writing that email to you. Can you please give me five minutes to send the full version, and then we can talk?"
Then ran into my boss to explain, and rewrote the email with a bit saying something about it being a great opportunity for us to share our knowledge, and how difficult it must be for them to implement this strategy (whatever it was the email was about in the first place) in a different cultural environment, and how I'd be happy to help with any queries.
Sent that off with fingers crossed. Boss got a phone call two minutes later saying how helpful I'd been.
Lesson to learn - don't write anything that you're not prepared to have read by the person it's about!
In your situation, if you've already apologised, it looks as though there's not much else you can do.