A lot of people miss that one. Still, Abraham was a coward, hiding behind his wife's skirt. He knew the intent of Abimelech, but instead of protecting his wife, he gave her up to protect his own hide. It was God who had to protect Sarah. Obviously, Abraham's faith hadn't been refined at that point, but God worked with him in spite of himself, just as He does with all of us if our hearts are sincere, so the bottom line is that none of us can really know this man's heart. Only God knows that.
She was still his wife, denying she was is still a lie.