Adipsia

I think you've almost answered your own question. You're staying in this relationship because however uncomfortable it seems, it's something that you know and you're attached to that familiarity. Also it sounds to me that your energy levels are totally depleted, you've resigned yourself to the position you find yourself in.

The hardest thing for me when my alcoholic ex left was the hole in my life. I knew that she was addicted to alcohol, but I had never realised until that point just how addicted I had become to her. How bizarre is that ? Why would anyone in their right mind choose to live in a relationship where their partner is constantly undermining everything that you hold to be good, decent and true ?

The fact is that I would never have chosen that kind of a relationship, the love that I initially gave freely became perverted and ensnared me. I think that's what has happened to you.

What you need to do is realise that time has moved on and the love that you had is no longer healthy for you... in fact, it's kind of like negative alchemy, your addictive relationship has turned gold into a base metal.

I'm sorry if that sounds harsh, it's a criticism of how I was, as much as you; but what I can say is that when you do overcome the initial shock of having a hole in your life, it's amazing how many positive things can come flowing in to re-energise you again.