You're almost 2 weeks out from d-day. The SI rule of thumb is that it takes 2-5 years to recover from being betrayed. Your life as you describe it - no sleep, no joy, hyper-focused on your betrayal - is normal for now. Your desire to R despite the advice you've gotten is normal for now. Your state of mind and spirit is normal for now.
The weeks after d-day were the worst period of my life. It takes more than 2 weeks to comprehend the devastation wrought by betrayal. It takes more than 2 weeks to comprehend the disillusion you have to go through.
Your life will get better, but not yet. What got me through it was accessing an 'observer/guide' in my head. My self-talk kept telling me that I was essentially going through a phase and that I'd come out OK. My inner guide told me to go for the best resolution I could get and that it might take me some time to figure out what that resolution would be. As I felt worse and worse as the depth of the pain became clear, my guide told me to ride the waves of emotion, to let my mind go the way it wanted to go, and to have faith in myself to figure out what was best for me. It took about 6 months for me to hit my rock bottom, but the length of time to hit bedrock varies widely.
Love is not enough for R to succeed, just as love from one person is not enough to cure another's alcoholism. That's a big sticking point to me. Alcohol is generally a depressant, and your WS is depressed already.
Is she addicted to alcohol? Is she willing to get treated for depression? If she's not willing to see the benefits of treatment for her depression and her potential addiction, she will be unable to change from cheater to good partner. If you stay under those conditions, you will be living with a time bomb.
She has to want to change for herself for the change to be effective. She has to take responsibility for herself, and she has to have some hope for her healing.
After 11 years together, I don't know if I'd leave immediately. That's not fallacious (sunk cost) thinking; rather, my bet is that you've built a lot of bonds in those 11 years, and a goodly portion of those bonds are likely to be healthy. It's not easy to cut those ties. I know I took 90 days to evaluate my options; others take/took quite a bit longer. There's no need to break off right now.
There is a need to observe yourself so you know what you want. If you truly want R, it is necessary to evaluate your fiancee as a candidate for R - that means, at the least, requiring no more lies, no more excessive drinking, getting treatment for her depression (with therapy, not just drugs).
First, weather the storm
Then figure out what you really want.
If you really want R, then find out how a good a candidate for R your fiancee is.
If she's a good candidate, great - you can start R and keep going if you both do your work.
If she's not a good candidate, or if one or both of you stop doing the necessary work, it's probably best to end the relationship....
[This message edited by SI Staff at 4:33 PM, Monday, October 31st]