What do you do, when you are married or in a committed relationship and you have a crush on someone else?

Do you try to tame your feelings, or destroy your life in the process of exploring those feelings, or avoid the person you have a crush on until you feel normal again, do you leave your spouse because obviously you have feelings for another....What do you do? I personally tame my feelings, I am not selfish nor do I want to induldge in selfish fantasies....I do love my husband, it's just that sometimes my heart goes astrey.