Do you love this man? I think you need to decide what he means to you and if he means a lot as you say then decide what that is!
Apart from his drinking are you happy with him? Or just afraid of being vulnerable and hurt again? You obviously were devastated by the loss of your husband so this relationship is a big risk for you.
I think you actually know yourself what you need to do. You know you need to be straight and honest with him.
Tell him how you feel — your worries and concerns. You would hardly be giving this much thought and time if it were not your business now, would you?
Tell him what you have told me here. He may have a serious drinking problem, never mind what it must be doing to his liver. This is not healthy. Go for it and tell him all. At least then you will know where you stand.
Be prepared for his denial but stick to your guns and be honest. At least then you will know. So all in all what do you have to lose? Take your courage in your hands and talk to him. Be true to yourself.