Well as you've clarified you care very much for your husband. Crush, is simply stating that you're attracted to someone for physical or emotional reasons (or both!). that's normal. You can analyze why til the end of time and likely won't have a definitive answer that satisfies you but the truth is, it is attraction, (or) lust, and is purely emotional. You are right if you dont' act on it, it really isn't any kind of cheating or doing anything wrong but for you in these situations, you are also correct in thinking you have to (not should, MUST) walk away when it is possible. I say "when possible" because sometimes it's a coworker or someone you have no option to avoid. But here we are talking about a game. So yes walk away and save yourself the distress it will cause you, because even if you never acted on it, the feelings can become unbearable and cause a lot of problems anyway. When you walk away it will be hard at first but that will dissipate over time. hang in there.

It's good he quit. Just dont' look for or pursue him. That would be crossing the line imo.