A good man wouldn't cheat on his wife or even go that route. DW you are treading on waters of no return once you go that route. Temptation is all around us, but at the end of the day the grass is not greener on the other side, and are you really going to throw away 20 years for a 22 year old chick that you have nothing in common with?
ALL relationships take work, and no one ever said they were easy, they will constantly take daily work, communication, commitment, honesty, and love. If you have no love, and you are looking elsewhere then maybe that is your cue to either not be in a relationship, or have a serious heart to heart with your woman at home and both of you pick up the pieces and start focusing on the relationship again.
Sex is a huge part of every relationship, and women are very emotional, they like to emotionally feel love, and if your woman is not giving it up then maybe you aren't feeding her need for emotional love and she just like you is going through the motions.
Given the position you are in, I would think back to a special date and time you had together and plan something again along those routes, start showing your wife the love you have in your heart for her and she'll open up to you again.