Nothing weighs on us so heavily as a secret.
— Jean De La Fontaine
I am glad you have asked this question. While the swoon of love sounds powerful, there are several things about your question that you may want to pay attention to. The most important are your contradictions. “I am being truly honest when I say there is no other man in my life.”
Such an interesting sentence for a married woman to say a man that isn’t her husband. The problem is you seem to believe this. Most of your adult life and relationship has been spent with you having a secret that was based on a lie. This is continuing. We are not typically drawn to what is necessarily better; we are drawn to what is familiar. You may find some more information in an article I’ve written here. Your husband has reason not to trust you, and you lied to him. You are creating the same thing with the new man. There now is a condition here where he doesn’t trust you – also because of lying. In both cases you are left in the same role of not feeling good about yourself—in your words “never forgiving myself.”
I would strongly encourage you to do three things: First, it seems clear that you are doing a huge disservice to your current husband. Let him know where he stands. Deal with the reality of your feelings and let him have the dignity of coping with the fact he is married to a woman that doesn’t love him and would prefer to be with another man. This condition isn’t just about how you feel. He needs to know where you stand.
Secondly, you must realize that you are drawn to unavailable men. This is the second married man you were attracted to, and the second time you were with a man while being attracted to a married man. This kind of thing tends to be a pattern. In both instances there was lying and secrets. In both instances you are not feeling good about yourself. Last time you carried forward the secret, which may have been the problem with your intimacy. I suggest you begin by being honest with yourself.
Finally I would encourage you to begin therapy as soon as possible before acting on my suggestions. This is likely to be a difficult process for you, for your husband, for your boss, and for his wife. With all this in front of you I encourage you to get some emotional support, clarification, and understanding before taking any action. The find help tab at the top of the page will help you locate someone in your area.