Mia
Sometimes in life, the memories of loss are what defines us as the person we are now rather than the person we were before. We wouldn't be who we are today if not for the experiences we've had, even if they're less than pleasant.
That being said, it's unfortunate that you have to deal with memories you'd wanted long forgotten. Take a deep breath and ask yourself why you let it bother you so much. Meditate on what about him still makes you care while focusing on your ability to care that much, and then transfer it to Jamie and your friends. He is long gone, Mia. He cannot hurt you anymore. You give him more power than he deserves by allowing him to affect you this way.