Obsessed with boyfriends ex?

I feel like i am obsessed with my boyfriends ex, everything he has seems to be connected to her in some way. They were together for 3 years, she was his first love. The thing is when they were splitting up (she dumped him) he was completely devastated (me and him were friends) and he would ring me up telling me all the gory details about what they were like together, how much he loved her, even the . They about 6 months later me and him got together. The first year was a nightmare, he was still bringing her up in conversation and i felt as if he wasnt really over her. 2 and a half years now its different. But i found recently he has a folder dedicated to just her, it has letters, pics (including nude ones!) cards and things from her. Im fine with memories but its in his cupboard, his parents call me by her name accidently, and if we are looking at family photos i occasionally stumble across photos of her, all the cuddly toys she got him are still sat ontop of his wardrobe.