Was Teresa Banks real or a figment of Laura’s imagination?

leland didn’t kill her (I highly doubt). obviously Bob didn’t kill her.
was Teresa real but was her murder just a figment of Laura’s precursor to her death dream? obviously agent Desmond and Philip Jeffries along with the rest of the FBI and blue rose task force were Laura’s imagination.

please somebody explain! I know that Lou Ming was also confused and had not yet figured out out what to make of the Teresa banks conundrum. what say you fellow Finf Laura studebts?