Currently, you’re married with twins, and if you want to be with this childhood friend, then you know you’re going to have to get divorced. Are you ready to do that -- separate from your husband and seek a divorce? I suspect that part of the attraction is the forbidden nature of your relationship and the fact that he offers you an escape from the day-to-day drudgeries of family responsibilities. He probably also flirts with you and shows interest in you in ways that your husband no longer does.
First, talk openly with your man friend about what his specific intentions are. Does he plan to marry you and make a family with you and your twins? Does he want something much less? Are you unhappy enough in your marriage that you want your independence regardless of whether this other relationship works out? Based on the answers to these questions, consider having a difficult but open conversation with your husband about your extramarital friendship to determine whether your marriage is worth saving.