Well, you asked for comments...
Up-front, let me say that I am not a religious person - I self-identify as a temporal agnostic
. So take this with a grain of salt.
I have often struggled with reconciling the religion vs desires thing. I have known folks from what I consider the "stricter" religions of catholicism and judaism consicously and repeatedly deviate from the tenets of their faith, and yet still call themselves believers. The catholics go to confession and then go out and do the same things again.. and again and again. Whether it's masturbation, use of prophylactics, sodomy, or infidelity. I guess for me, if I am not willing to even make a sincere attempt to live by the rules of a religion, then I really don't feel like I belong in that religion.
If your faith is important to you, and it sounds like it is, then I think that you need to work hard to reconcile what you are thinking of doing with the teachings of your church. As others have said, just because you are tempted to break your marriage vows (and my understanding is that your vows are not negotiable after the fact, having been exchanged in a church service) doesn't mean that you should.
This is temptation in its purist - you are being tempted to do something which is against the tenets of your religion. It is an incitement to sin. From my (limited) understanding of your religion, temptation itself is not a sin, it's only when you take action to give in to the temptation that it becomes a sin. Temptations are permitted by God to give the faithful an opportunity of practicing virtue and self-mastery.
My advice would be to reconcile in your mind and soul the conflict that is going on between your Catholic faith and your desires. If you wish to remain a sincere Catholic, then I think you need to resist the temptation to sin.