It's OK to miss someone. I was just thinking this morning about my second alcoholic husband, whom I left more than 15 years ago. Sad that it didn't work out, but honestly, I am so much happier and better off than if I had stayed--it would have been an ongoing nightmare. As far as I know he's still drinking.
OTOH, I spoke yesterday with my first alcoholic husband (who was sober before we got married and still is, 35 years later). I still enjoy talking to him, miss him from time to time, but we keep in touch and I think I made the right decision for both of us.
Now is the time to think about your future. It's wide open and can be whatever you make it.
Hugs,