Dear girl in love,
Your pain should tell you to stop, not your head. Your head is right.
His feelings are confused at best. He clearly wants to protect his marriage and reputation, and he cares more about those things then he does about you.
It's okay that it hurts! Your heart is responding to this hurt by saying you love this guy? Listen to what your heart is really saying. It's more likely saying, "I want to love an established, secure man, who knows what he wants and how to get it. I want to love this man, because he wants me sexually. I want to have sex with this man because he's satisfying a part of me that wants this attention and be desired by someone like him." These are wants. These are desires. These things are not love. Your heart wants him, but you are not really in love.
He's getting what he wants, and on some level so are you. But, watch out. There is real pain here. His feelings are not what you really want from a man. He does not love you...can't really love you. You are too young. According to US law, he is raping you and you are incapable of giving him the adult permission to have sex with you. Of course he doesn't want you tell anyone, he could go to jail!
Love Shouldn't Hurt This Much
Listen to the real feelings. Listen to the confusion, the pain, the desire...but call it what it is. As Keb Mo, blues singer, said, "that's not love, if it hurts that bad, that's not love if you feel so sad, I don't know what it is, babe, but that's not love."