yea i know how you feel...except like not that extreme, my ex dumped me last year on christmas, day before our 7 months aniversay, and then dates another chick like a week later, he claims he didnt...
the only way i know how you can erase your memory is Amnesia, and you have to hit some part of your head to get it, however amnesia it can last a lifetime or just for a little bit so im not so sure...