First of all talk to your boss. They usually understand. Second, join a gym and start exercising it'll help clear your mind. You can't concentrate on two things at once.
If you're smart you'll file as soon as she separates. Separation is for her to spend time with her other man.
Laying around in limbo will not get you much except more wasted life you can't get back.
If you were wanting to try and save this exposure is about you're only weapon.
Being weak and affraid is your worst enemy. Unless as your doctor recommended you can "man up" you'll just linger longer.
Do not contact her at all. The worst thing you can do. You chase they move farther away. That goes for long stupid letters pouring your heart out as well.
All of this. Definitely talk to your boss. I was a mess during my separation/divorce--it opened a Pandora's jar of all these emotions that I had been suppressing my entire life, and it affected my work performance, unfortunately. If I hadn't talked to my boss about it, I could have lost my job. But he was understanding and we were able to make some adjustments so that my workload as more manageable.
~Happily un-married since December 9, 2013~