Shockingly true what you copied and pasted from the stickies isn't it? Hard to accept but it is what you need to read over and over and over. We try to reason the why's away and come up with any other possible answer except for the harsh truth because sometimes the truth really hurts.
Yes, she needs to be alone in this recovery because she is either going to quit or she isn't. You cannot help her nor save her. She has to want it herself.
You have your own family, CHILDREN who need you and should not be subjected to any of this nightmare.
I did want to comment on one particular comment you made because it so resonated with me
"What I do know is that if someone... anyone would have stuck with me and gave me some guidance at an earlier age, then I might not be where I am now. Late to the game, and scrambling to play catch up building a life. But I digress..."
I grew up in a ****** household with two parents who were extremely selfish. My mother never failed to tell my sister and I what a burden and pain in the ass we were to her. My dad ignored it and did his thing. I cannot tell you how many things I did and used that as an excuse for my behavior. I finally smartened up and found a really good CBT counselor who after a year got me to where I am now. Just like she cannot use her drugs as an excuse to cheat and lie you cannot use that excuse anymore to hang on to a drug addict who could actually give you a disease that can kill you from an STD. I am not trying to be harsh, honestly I am not.
At some point we have to be accountable for our own actions and decisions and not blame it on anything or anybody else from our past. I am speaking from experience here. Ive done just that. Many times over. We are both adults perfectly capable of making good or bad decisions.
It really doesn't matter anymore why you picked her and have had a relationship with her just like it no longer matters why she stuck with you or what you may have done or not done in your past. You are dealing with the present and right now she is in rehab and you had to send a self addressed envelope to get a response. Do you really want to keep doing this?
My advise for what it's worth? Keep going to counseling (I strongly recommend CBT), stop worrying about fixing her and work on fixing yourself. It is hard work but you will be a much happier person inside and it will help you make better decisions. You DO deserve better despite what you think.