How is it possibly to lust after a man who broke my heart and put little value on my self worth.?

I will never go back to the man who mentally, verbally, and emotionally put me through the worse four years of my life. He was an adult 30+ year old alcoholic pot head who lived with his parents. I am worthy of someone better, this is why I walked away. I know this! Oddly I have been having strange emotions/feelings lately. Which leads me to these questions. Why do I reminisce about our sexual and physical encounters and jealous of the thought of other women receiving that pleasure? Any input or suggestions on how to get rid of these emotions are greatly appreciated.