We all make mistakes. Does that mean it was ok what you did? You and I know it wasn't. BUT we learn from the things we do. Hopefully you're husband is understanding but the best thing to do is sit and just be honest.. that choice will have to be yours obviously. But it's just better to be honest and come out. As far as herpes goes it's really no big deal, it's more just a thing you'll have to deal with here and there. It's not gonna kill you and you're gonna live a long full life. As far as passing it on just keep your hygiene up and wash your hands every time you touch that area, etc.
But trust me, you'll be fine. God is with you. You messed up, we all do. 100% of us have a period of time that we wish we could go back to but the only thing we can do is look ahead and better our future!