where are the nukes?

And it's been 5 years already, here I am talking to another girl and I can help it but to think about my ex from all those years ago, I just can't get her out of my mind, it's as if she was truly the peak, the most valuable thing I ever had. Not a single girl I see is as beautiful as she was.
I want this to stop, what can I do? why am I still obsessed with her even when I know all the bad shit she did and does I can't believe I'm still in love with her even when I haven't even seen her in years