Let me start by saying I am sorry that you find yourself in this situation that so many of us are in. I know what you are going through with the anxiety and the weight loss and the anger. We have all pretty much reacted like you did when were first found out and didn't know how to behave any better... take heart in knowing that so early on it is likely your wife doesn't really know what she wants. Giving time and space can work in your favor, filing for divorce so early probably will not.
I would tell her as soon as you can that you have divorce papers coming her way, but that you have changed your mind and don't want to carry on with that yet. Tell her you understand that she may need more time to process her feelings about you and the other man and come to a decision (make sure YOU understand that in granting her time you are opening yourself up to a long wait and no guarantees).
And I know about the anger and the cycling between being a decent, loving human being and your most angry incarnation. I was there in Angrytown myself just today, even though I really ought to know better.
Keep reading the DB book, read all the threads in the newbie resources section from Cadet. They are SO helpful. I have started taking notes and printing off copies of some of this stuff so I can have constant reminders/reinforcement to review when I have the time.
Being calm, being patient, being loving from afar, being quiet, being "dim/dark", giving space, letting her initiate the interactions... all those things are what YOU can do to make it easier for her to find her way home. You can't force her into making a decision before she is ready, if you do it will backfire. She will make the only choice she thinks she has right now, which is escape/avoid.
I am only 5 weeks post bombdrop myself, but I was lucky and stumbled onto this site much sooner. It is not an easy path, you have to decide if you are in it for the long haul, because there are no quick fixes and there will be plenty of bumps in the road and you will make mistakes. The good news is that most of our runaway spouses are still not as certain of their decisions and intentions as they state. It is our job to step back and let those doubts continue to grow and work on making ourselves a spouse they would be a fool to want to leave.
me-35 WAS-37 T-16 1/2 Son-14 (HF Aspergers) BD,ILYBINILWY,"I met my soulmate": Oct5,2013 "Letting go because I love him, holding on because I love him."