somebody who was your bestfriend at one point but then backstabbed you or started to ignore you and is no longer your bestfriend.
you usually have strong feelings of hatred or sadness toward this person.
nikki- "idk what happened with me and emily"
friend- "i thought you two were bestfriends?"
nikki- "emily started ignoring me and i guess i was replaced. i love her to death but idk what we are anymore"
friend- you're exbestfriends" :(