Fathers-in-law often get to be the "fun" parent. They don't have to enforce bedtimes, manage the family budget, or decide who is cleaning the bathroom this week. When your father-in-law visits, it is usually for holidays, barbecues, or leisure. He arrives with a joke, a toolbox, or a story, and then he leaves.
Do not throw away your marriage over a feeling that is actually a symptom. Use this revelation as fuel. Go to couples therapy. Hand your husband this article. Start a fight if you have to—but start the right fight. The fight for intimacy, not the fight about whose father is better.