I can understand your husband feeling betrayed by that specific relationship. However, he has come into awareness that such love is possible without diminishing the love he currently has. So he should be working towards acceptance of your love since he has found additional love as well.
He should try to understand how he would feel if he losy his current love and realize that is how you feel. Hopefully by tryiong to empathize, he will be able to handle the relationship you want to rekindle.