Your feelings aren’t “overboard” but your actions are. Your note to your husband is so angry that he probably can’t think of anything to say to you. You certainly had a right to express your feelings. Now go back and invite a conversation. The trust in your marriage has suffered damage from both of you. He’s secretly talking to old girlfriends. You are snooping in his email. If you want to save your marriage, it is time you two had a heart to heart about what is really going on between you. If you can’t manage it by yourselves, please find a marriage counselor who can help you listen to each other and maybe find a way to reestablish the trust that is essential to a marriage.
I wish you well.