Why would you want to be with someone whose girlfriend has their balls in a choke hold? He needs to man up. I am not even being sarcastic. I mean this in the best way possible.
If he is a grown man, he should be in control of his life and his affairs. At the end of the day, he has to live for himself and not for her. He should not have to pitch an idea like he is meeting with the board of a company in order for them to manufacture and sell the product.
He must like it because he let you walk away. Maybe he likes being controlled. Whatever works and floats people's boats. If he loved you or even liked you, I doubt he would have let you walk away that easily. He needs to figure out what he wants and lay down the law with his girlfriend. You need to stand your ground and be firm. Confidence is your friend. It is okay to be shy, but when facing him, straighten up, look him the eyes, and listen to him, and lay the facts out. "I am not your sex toy. I am a human with real feelings, and I do not appreciate being treated like...."
Resist the oh so sexy muscles, the spiraly curls on his head, the scent of his cologne, the smell of his tooth paste, the aroma of his aftershave, the piercing depths of his eyes that are windows to his soul, etc. I know you did not say all of this, but I wanted to add that.