I know that you see yourself as a superwoman who has the ability to fix everyone’s problems and to help this guy get back on track. However, this is nothing but an attempt at emotional manipulation.
Even if you have the desire to walk away from this man, you feel obligated to stay. By saying this, he is putting his life in your hands, which is a responsibility no one should take.
He is burdening you with baggage that you shouldn’t carry around.
Besides, this man is obviously quite troubled. He wants you to take over his demons and is trying to pull you into his darkness.