Your dilemma Jim is one that many guys face as their sexual feelings and mortal awareness surface in later life. Do not feel dirty or guilty about these desires as they are common in men.
Perhaps you need to try man2man sex with an experienced facilitator and then asses your marital relationship and how you can protect those you love. Whatever you do, do not die wondering what it would have been like to suck and enjoy a horny cock or have some virile guy furiously fuck your body because he wants to. We have needs, we have sex and we love. Humans are odd spiritual creatures. Jamie