While I was married I twice experienced a serious crush that came on suddenly and really strongly. My marriage was very lonely, and my husband unkind, so no surprise that both of my "crushes" demonstrated genuine kindness towards me, and that was a big part of what drew me.
However much I loved feeling so alive as I did when I experienced the excitement of these crushes, I knew it was wrong, to "commit adultery in my heart". I certainly knew I wouldn't want my husband doing this. So I was not happy with myself in this situation, however, willing myself to stop it did not stop it. I found that to stop it I needed help outside of myself, or, supernatural grace from God.
I thought of the holiest people I had read about, and a common thread in their lives was some form of confession. So I made a "confession" face-to-face of my problem with someone else. I picked an older prayerful woman from my church and asked her to pray for me, and told a couple other prayerful friends by phone and asked them to pray. I cannot tell you how powerfully it breaks the sin if you confess to another, if it is no longer a secret in the dark, unbeknownst to anyone. (I doubt anonymously sharing it on the internet helps much). That and avoiding the person was the key to gettign over the crush. So it was:
1. Confession to another, face-to-face
2. prayer for God to help me get out of it
3. avoidance
The second time "getting over it" went a lot faster because I knew what to do. Now I am Catholic, and would just go to confession over it. Confidential, and efficacious!
Once also when I was married, I mistakenly, out of the blue, completely unplanned, gave a male colleague a "help me" look at lunch. It was a fleeting look, but he about fell out of his chair, and completely changed his demeanor with me after that. As if I had said, "Come hither!" I was so embarrassed, I did not want to start somethign up at work or anywhere else! I just completely avoided him after that. Which was hard, since we had meetings together. Things eventually returned to normal...
That and the other incidences should have told me, something was seriously wrong with my marraige! I knew it wasn't good, but it was a seriously disordered marraige I was in and I had no idea how very bad it was at the time.
So because of that, I would suggest that maybe if you are vulnerable to a crush, there might be some serious flaws in your marriage that you need to understand better, and address, if possible, with a good counselor. Some advice I got at the time, which I now in hindsight think was on target, was that if I was vulnerable in this way, my husband was in some way not loving me properly. (That was sure right! I wish someone had emphasized to me that to be loved was a normal expectation for a marriage.)
Also, another point which turned out to be true was that if I was experiencing this attraction to another man, likely, at the same time, my husband was experiencing an attrraction to another woman. The woman who told me this said she had seen it over and over again.
Turns out, he was flirting with another woman from his work at the time. I saw this clearly at an office party spouses were invited too, but did not dare confront him because he would ahve denied it and said I was crazy. So how I dealt with that is another funny story - I "love-bombed" him at work, sending in treats to his co-workers, a giant tray with three kinds of homebaked cookies one day, a massive vegetable dip tray another day, and I was arranging a "just because I love you" singing-gram with balloons when he called me from work to beg me to please stop sending gifts since it was getting him so much attention/questions/jokes at work about what his wife was up to... Well, I did make my point, they could all see he had a wife who cared at home, making it a little embarassing to always be slipping out with his coworker... That was lots of fun. Its a long story I won't explain, but later this tight friendship did break up, and the woman's husband, whom I had met only breifly at some previous office party, approached me when I arrived at the company picnic that summer and gave me a great big lingering hug. For giving his wife back, I presume. Yes, that was an adventure, but our marriage was way too broken to be fixed...
