You are fortunate to have found this board. I was where you are EXACTLY, and I stayed on the merry go round for another 12 years and got divorced anyway in a train wreck of lies, infidelity, and alcoholic chaos. Read as many threads as you can.
For me, I bounced like a ping pong ball with I forgive her (it's a disease) back to oh my God this woman is a lying entitled princess manipulator! XAW went to every form of rehab and has 100% perfect track record of relapse.
What always drew me back, was how incredibly freaking kind and nice she was when sober! Almost like an angel. She could be so awesome and I wouldn't want any other woman. So what I have learned unfortunately, is that I can't trust it to stay that way. It will go from heaven to hell, over and over, that is my personal experience.
If you stay strong and get divorced including telling while she is in rehab, I will be impressed and certainly would commend you on your emotional strength and power of your convictions. God bless and all the best to you!