I'm so sorry you're going through all of this
18 years is a long time to be married and you've got a lot invested. I'm not sure if you've already tried but maybe marriage counseling as a last resort? The person you're with should make you feel special and better about yourself and you deserve that. I wish you all the best and hope that you and your husband will be able to work this out and that he'll be able to give you the love and respect that you deserve.