What you should do all comes down to one question. It is simple.
What do you want for your life?
I read your post as a "veteran" of this complex condition... known as co-dependent. That is why they term alcoholism as a "family disease" - cause it really messes with emotions of everyone in the family. We find ourselves on this "merry-go-round" and the whole world is spinning so that everything is a blur. Confusing. Yes!
Make yourself a list (pros and cons) of your relationship with this person. Pin it up in your bathroom, and read it every morning. Let the thoughts settle and let it help you make a decision for what is right for YOU.
I will say, the longer you stick with this relationship, the harder it is to free yourself from it! Add in financial obligations/marriage/children it becomes very difficult.
Best wishes!