What if you told your pastor exactly what you have said in your letter to me (only in more detail)–that everyone thinks your marriage is perfect but in reality it isn't? This might help him understand your situation.
In any case, he might be surprised by your admission–but I doubt if he would be shocked. Pastors see far more of human weaknesses and problems than most people realize, and in my experience they are seldom naive or unrealistic about our frailties. Besides that, your pastor cares about you, and I have no doubt that he will want to do everything he can to help you. If he feels he isn't the best person to help you, he'll probably refer you to someone else.
The most important thing you can do, however, is to turn to God and commit your marriage to Him. God brought you together, and when you made your vows to each other you also were making them to Him. Jesus said, "Therefore what God has joined together, let man not separate" (Mark 10:9).
If you have never done so, ask Christ to come into your lives–and your marriage. He loves you, and He wants to help you overcome your problems–and He will, as you open your hearts to Him. Then ask Him to give you a new love for each other–a selfless, sacrificial love that is like His love for you.