Sorry you're hurting right now. Get it all out and then start talking some sense.
What changes have you been doing? Your W is messing around with another guy. Start getting some self-respect for yourself. That's why your W is being attracted to the other guy right now. WAW's in particular will usually jump ship when they have someone else to jump to.
Have you been working on the weight? Get up and yell, scream, do whatever, but DO NOT think that you aren't worth getting your W back. You got her to marry you. You can get her back. Remember that.
But you've got to start getting self respect for yourself. I put up a link of inspirational items to start rebuilding yourself. I'll repost it.
M-43 W-40 2D - 9 and 5
Emotion, yet peace. Ignorance, yet knowledge. Passion, yet serenity. Chaos, yet harmony. Death, yet a new life.
