Mine does the same. I have the little voice in me that knows better, but always feel I must "show him the light", that I am NOT who he says I am. That the relationship crumbling is in fact due to his drinking and choices not to work on it when I've been the only one working on myself. I'm no perfect girlfriend (very codependent!) but I have tried to work to make it successful. Though he is unable to meet me there.
What I learned is that it is ok to let go. Who they say you are and what you've done is their addiction talking (your response is your codie voice talking back maybe?). Yes, quacking. It isn't real. It is usually a manipulation bait thrown out there to get your attention (and it works!). Take a deep breath and know your truth is all that matters. NC will allow you both (at least you), to heal.
Reminds me of a line in the movie "Couples Retreat" where Vince Vaughn's character is being doubted by his friends and he keeps repeating, quite comically, "I know my truth". It's a funny scene and funny line but I love it. He doesn't care that his friends don't agree on his exaggeration he was bitten by a shark because all he knows is what is real for him. I have said this even to ABF before.
You know your truth.