Your husband sounds scared you will discover, after meeting others and having fun with them, that he won't be needed. The frail male ego, though women are just as bad in many cases.
He is wrong that the relationship with him is all you should need to be happy, we are social animals, it's not good or bad to be that way, it just is what it is. He is used to you being shy, and breaking that shell is making him wonder if you are going to leave him. If he wants to be a potato and grow roots into the couch, fine, he wants you to do the same and you don't want that, and there is nothing wrong with that.
He has issues HE needs to deal with, with your help if you choose to stay with him. Your screen name shows you are being put upon by him, maybe some 3rd party intervention may help?