If you have looked with lust you are an adulterer at heart
Jesus made it clear that sinful desires have their origin in the heart. This includes adultery.
Please think about what Jesus said in Matthew 5:27-28...
"Ye have heard that it was said by them of old, Thou shalt not commit adultery: But I say unto you, That whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart."