Although Jacob counts her among his enemies, Bella still considers him her best friend. But doesn’t it take two people to have a friendship? Or, in other words, can you be friends with someone who regards you as an enemy?
Not to mention, it's interesting that Bella identifies Jacob as her "best friend." That seems to imply that, while Edward may be her true love, he's not her closest friend. What's the difference between being a true love and a best friend?