[This message edited by BrokenJohnny at 4:26 AM, December 27th (Friday)]
Lots of complexity to your situation. I don't have direct experience with addiction, but I know others here have. It's a bit slow right now due to the holidays, but hopefully they will weigh in when they can.
I don't know that you can make any headway on reconciling until your fiancee's addiction has been addressed. And it bears stating the obvious - you can't fix that for her. It's entirely on her shoulders. You can be supportive, but I'm concerned that you are stuffing your needs to your own detriment.
My advice, for what it's worth? Seek out support from Al-Anon for help in dealing appropriately with her alcoholism. And then focus on yourself. You DO need to talk about what you are going through. If she's not willing/able to support you, locate a counselor who can and will help you process all of this. Do not sacrifice your well-being by rugsweeping things.
"Ring the bells that still can ring
Forget your perfect offering
There is a crack in everything
That's how the light gets in." -Cohen
It's a long road to "fixed and whole", but you can get there together. Doing the work on the foundation will build a better relationship. It sounds like there were some blurred boundaries for both of you throughout the years. (Drunken 4some with friends?) and I think that things like that need to be addressed and laid to rest to protect both of you from future betrayal.
You are in good company here. We all want to be fixed and whole, and to help others get to that point along the way.
For last year's words belong to last year's language
And next year's words await another voice.
And to make an end is to make a beginning. - T.S. Eliot