Jesse James' Ex Wants to Be BFFs with Sandra

Jesse James' ex-wife Janine Lindemulder -- who's currently in a custody battle with the West Coast Choppers CEO -- wants to be best buds with Sandra Bullock ... all because of her little girl Sunny.

Earl Miller -- Janine's confidante and the photog behind FreeJanine.com -- tells TMZ, "[Janine] told me her greatest wish was for her and Sandra Bullock to become friends."

According to Miller, Janine wants to show Sunny that "the two most important women in her life" -- i.e. Janine and Sandra -- are good friends "who loved her very much."