Yikes! I can imagine how you freaked! I've done that with emails at work, and sent it to the wrong person... it's like H was on your mind and you accidentally clicked on his name for the text. Completely understandable and hopefully H sees that as well.
You're right though - you need someone to vent to, just as he admitted he's confiding in OW and he doesn't have any justification for trying to control who you talk to, IMHO. I bet you'll feel better after a good night's sleep.