Sorry CB - no magic wand. I don't even have any great advice but I just wanted to throw in my 2 cents. I'm sorry you're hurting. I know exactly how you feel and there's really not much you can do to feel better. Time does heal. I know it's difficult but try to get your mind on something besides the OM and all the drama: movie or night out with the boys, dinner with your kids, take some classes at a local college, get involved with church, scouts, etc.
Ambien is so strong. Have you tried Tylenol PM? When I've had trouble sleeping I have taken Xanax. But you shouldn't take it long term. It's not a sleeping pill, just an anti-anxiety drug (which helps you sleep).
When you have contact with W, my advice - Focus on the friendship. Pretend she's a good friend. What would you say to him/her? Do not say "you seemed distant." You wouldn't say that to a good friend or someone whom you were just starting to date. Don't say anything that appears to be pressure. Remember, the OM isn't pressuring. He's probably telling her how wonderful she is. Maybe say, I love that red sweater you have on - is that new? Or would you like to join me for some pizza and beer before we go to bed? Or, bring up funny stuff - anything that will make her laugh.
Great advice from Steve. All of it. Absolutely NOTHING negative. Your words, attitude, tone of voice, body language, etc. You really do have to become a "different person." Act happy, optimistic (you can cry later when you go to bed alone). You have to become an "actor."
Yes, this is all difficult and painful. But, if you play your cards right, you may just win this game.
And go ahead and resign yourself to the fact that this will take some time. Try to do some things that make you happy by yourself in the meantime: the class on photography or cooking, the gym, your reading, etc. In the past year, since my GF left I have gotten my master's degree. I will graduate in August. It has kept me busy and given me something productive to do besides mope around, cry, thing about her, read about relationships ALL the time, etc.