This will sound harsh, and I don't mean it to, because I know it hurts.
You are not married to this person. You have no children together. Run. Run away as fast as you can. It does not mean you don't care any less, it means this person is not good for you. It's ok to love someone from afar.
Being with an addict long term brings nothing but heart ache and hurt for all around them. It does not make them awful people, it makes their life toxic. I will say that I would never be with an addict unless they have very real clean time and have worked recovery for a LONG time, and I mean years.
Again, I don't say any of this to hurt you, but to let you know that you have a chance to move forward from this.