Sorry that you find yourself here. Candidly, booze is not going to do anything to help this situation and I would urge you to give it up and find some other outlets. Exercise is a good outlet to help you de-stress, take your mind of the situation and the other benefits of exercise come to both mind and body. Rather than drown out your feelings with booze, use natural post-workout endorphins to help boost your mood.
Have you consulted with a therapist so that you can get some counseling? What you have gone through is a tremendous trauma and honestly, no one should try and go it alone. I think infidelity and dealing with in my life has made me a theraphy-evangelist in the sense that everyone should talk a therapist, because I've kept up with my therapist and it has been tremendously helpful in dealing with other things from my past and present. For example, my wife and I have been in a reconciliation mode for almost 3 years now, but last December I had a major betrayal by someone who I considered a friend, a longtime mentor and unfortunately also my boss. I was a wreck for a couple of weeks and I reached out to my therapist and he really helped me to reframe my thinking and my own internal narrative and it has really helped me to recover from that event and I'm in the process of getting a new job, thanks in part to his counsel.
She cheated on you and left you. If there are no children between you and no shared assets to divide like your home, we have a saying around here, no contact means no new hurts, and I would highly advise you take that under consideration. She kicked you out of her life and it is time for you to do the same with her. Take out your phone right now and block her phone number so that she can't call or text you any longer. Do the same with her email address, any social media accounts she could use to contact you, etc. I get the sense that she moved out of your home, but if she left anything behind or there are photos of the two of you or anything like that, love mementos, I would box that shit up and stuff in the the garage or the trash. I get it, you cannot shut off your feelings for someone in just a few months/weeks, especially after 14 years together, but you continue to allow her to be a source of pain your life. Her MS diagnosis is awful and you can be an empathetic person that she is suffering, but she fired you as a partner, so you are under zero obligation to expend any more energy supporting her in any way.
I guess my advice is to move on one step at a time. I give you tremendous credit, you self-reflected and came to the conclusion that you need help, because you were spiraling with booze it seems. All of us here are more than willing to help you and provide you support in this difficult time, but the reality is that only you can change your situation. Again, those of us who have been down this road are willing to support you and understand that the wisdom we share with you has been hard won through thousands of betrayed partners suffering and learning how to deal with their cheaters and the gruesome aftermath. No contact with her means she cannot keep hurting you and dragging you along. It is completely within your power to put an end to it and I truly think that move is the first step you can take on your healing journey.
I will wrap this up, but another quick anecdote from my past that doesn't involve infidelity. I started dating my first love/first serious girlfriend my sophomore year in high school. We split up a couple of times, but we did find our way back to each other a couple of times. We attended different colleges but we weren't far from each other (about 30 mins drive). I was on a track for med school and she was studying to be a elementary school teacher, so entering our junior year in college, I am still staring at years of school and she was student teaching, on track to finish school early, etc. We were at different places in our lives and she was putting pressure on me to get serious about marriage and starting a family. Simply put, for a number of reasons, I was not in a place that I could commit to being with her in that way, even though I loved her dearly. We split up over that and I guess for her, that was the last straw. Post split, we stayed in touch for a time, probably on the scale of days/weeks, but contact wasn't frequent enough for me to notice that she had blocked/ignored my messages and my calls were no longer even getting through, straight to voicemail. Years later, through her running into my mom and dad back in our hometown would I even get a glimpse into what happened. She had told my mom that she couldn't keep being hurt by me and so she had to cut me out of her life completely. At the time it happened I was upset, but looking back on it today, what she did took tremendous courage and guts to do, but it also was the exact right thing to do given how she loved me but she had to let me go because I was the source of her pain. Your partner is the source of your pain and while you may still love her, you have to let her go, because unfortunately, she has made it quite clear through her actions of leaving that she does not want to be with you. It is a tremendously tough pill to swallow, but one that must be swallowed.