When I first started dating my boyfriend he kept from me that his best friend and business partner was actually his ex,I found that out around our third month dating and made him confess, he said he didn't want to worry me for nothing.
She was his first love and they had a two year relationship that ended when she left him for another guy, apparently there was a lot of fighting and cheating involved (I don't understand how can they be friends after that) . I found out that she was more than just any friend just by the way he talked about her, but he acted weird e and he very time she called kept sending her mails just to say hi and send her pictures of him.
It took me six months to make him put away the picture of her that he had in his room, and a few arguments to make him stop saying how he would like to kick her boyfriends .
I talked to him and he swore he had no feelings for her and that he loved me but when we where moving together (about one year of dating) I found out that he still kept her letters and gifts, we have had a lot of discussions during our entire relationship about this but he always ends up crying and saying that he can't live without me and that he loves me.
We have been together for three years now and he still keeps photos of her in his album and refuses to get rid of them, he doesn't seem to understand that when I see her o he mentions her I remember all and I feel that he is with me just because she doesn't want him.
Its very painful to know that after three years together I am still not important enough to make him forget about her and throw all her stuff away.

He is stuck and your only chance of survival is to get out and move on. Otherwise one night in the heat of passion he will be calling out her name instead of yours. Or has he already done that? Unless he is willing to put that "first love" behind him you are doomed to always be in her shadows. Is that what you want?