"honey, I need to talk to you about something. I'm gay...." And then from there the conversation will take care of itself. You could always write it out in a letter, but I think that conversation would work. Just don't do it when you're driving, or when she is somewhere that she has no escape from. At home, with the radio and TV off, would be a good place. Believe me, it's better to do it now with only four years married than to get in any deeper. It only gets more difficult the longer you wait. Good luck! (*hug*)
Wildside is right. There is no easy way to come out to your wife so if your looking for one, your not going to find one. I know it may be difficult and it will be but it is better to do this now than later. The sooner you tell you wife the sooner both of you guys can find the one you are meant to be with. You may want to seek couples counseling so you can tell her there and the counselor can try and help you guys out. Don't wait, the truth sets you free. I know you really don't want to hear this but you have to tell her very soon. Best of Wishes ~Aidan
Agree with Wildside too. You have to do it. Suppression won't work, I've tried, ends poorly. I assume no kids, since you didn't mention it? Would you stay with her? I ask because I'm obligated to. My wife helped me financially through graduate school, so while most others were eating ramen I was eating salmon. And we have a daughter and they're both financially dependent on me. We are moving toward poly.
To be honest it is an extremely difficult situation you find your self in. The way that I came out to my wife was that I just broke down and started crying. Luckily I got a good reaction. No matter how you do it, and there are millions of ways of doing it, coming out is a scary thing to do. I would suggest you contact your nearest "Gay married men's" support group through the local LGBT support service. I've found great support and inspiration there. Best of luck. (*hug*)
Consider how you want this situation to end up. If you do not want to remain married to your wife, and want to move to a relationship with a man, then you are moving towards a divorce. You can come out to her before the divorce, or simply tell her that you no longer want to be married, that there is nothing wrong with her, but you need to move on; hopefully that can be a "no fault" divorce. Whether you tell her or not afterwards is up to you. People get divorced all the time, simply because they lose interest in each other. If you want to stay married to her, assuming she wants to stay married to you after she knows, then you are going to have to explain to her what you want and see if she can accommodate to that arrangement. I doubt, given your age, that she would want to spend the rest of her life married to a gay man, but you never know.