How do I stop being unfaithful to my wife?

This is real and I hope the mature men reading your blog can help me. I am married to the most wonderful woman in the world. We dated for four years before I married her three years ago. We are blessed with two kids and hoping to have more in the future. My wife is simply the best. She's caring, honest, giving, very respectful and responsible and on top of all that she's drop dead gorgeous.

 I wish I could show you her pictures to see but that would give me away. I couldn't have asked for a better woman. In fact my biggest prayer is when I return to this planet in another lifetime, I hope I marry the same woman. The only issue is that I am not faithful to her. I actually have never been faithful to any woman in my life but I feel this woman deserves that from me, I just don't know how to give her that. I've been with several women since we got together 7 years ago but lately I've been feeling she deserves more from me. I want to be faithful to her but I just don't know how to. I promised myself that 2013 was going to be different and I stayed faithful until last month. I've been with two other women since then, but God knows I want to stop. How do I break away from this behaviour? How do I stop myself from wanting and sleeping with other women? Serious advice only please.