How do i get him to stop looking at this bimbo?

My boyfreind crushed on a girl for 3 years before he met me. Some of his fondest memories are with his group of freinds that this girl use to be a part of including her come and go boyfreinds. My boyfreind and i have been dating more than 2 years and we live together. However he is constantly reffering to the past and all the good times and fond memories he has had with that girl her boyfreinds and all his freinds. I dont give 2 cents about this girl because she caused drama for our relatioship when we first started dating, and the only thing his group of freinds had in common was that they all worked together. Now that they have all gone their seperate ways theres no common denomonator. Other than the fact that they were all once reaally good freinds who partyed together. Whenever i try to stop him or tell him i dont care about those "fond memories" he thinks im a major beotch. Now i just sit silently bleeding at the ears having to sit through storys of the bimbo and all his freinds. we still get together with his group of people everyonce in a while but i guess its just not the same as partying it up smoking weed and crushing on a girl who never liked him untill i came along and saw she wanted what she scouldnt have. So do i have to keep hearing about this long lost lover of his or is there some way i can get him to shut the eff up about his past.