OK, time for a male perspective here!!! Not Dave, you'll just have to settle for good 'ol Jerry here..
Clarissa, I am so sorry to hear of this, but what I find equally troubling is your self-esteem issue...IMHO, you have no reason to have low self esteem, and I'd be proud to call you my friend any day of the week and twice on Sundays!! I don't want to get too caught up on the self esteem issue, just know that you are quite the success!!
DW's and I's relationship is built on a tremendous amount of trust, and she has no problems with me being a member of these boards, in which females are obviously the majority by a good margin. I simply told her I was joining, why I was joining, and she was cool with it. Ever since I gave up alcohol and my bar stool friends, I don't have a ton of friends either, actually, some of my wife's best friends have become some of mine as well.
My wife has zero problem with me attending Cathe's road trip, and once again being in the minority..once again it comes down to trust.
Had your husband told you what he was doing, this'd be a different story, quite possibly. You've gotten some great advice from some great friends here, and for what it's worth, your husband is just plain wrong, not so much for opening the account, but for not letting you in on it.
Take care!!