Put the condensed milk, cream cheese, lime juice and vanilla in a food processor fitted with the steel blade, and process for 5 minutes. ( Or beat in a mixer fitted with a wire whip for 15 minutes.) Spoon the filling into the cooled pie crust, and refrigerate at least 8 hours, until filling is firm. Whip the cream with the sugar until soft peaks form. Spread on pie. Garnish the pie with lime slices. ( I couldn't found Key lime juice so i used regular lime juice.)