Don't over-involve the in-laws. They are on your side, but they can't and won't control him. The battle will not be won in their living room. If he is willing to stay for 2 years, then you have time to make an effort to make life at home pleasant enough that he will want to stay. Many things can happen to that other relationship in that time that will make it less appealing. Keep working on yourself. Start working on dropping some of that excess weight. Keep up the sex life. Spice it up. My H's OW lost the battle in my bedroom. Yours can too.
