M.R.
100% normal separation anxiety that manifests around this age.
Keep taking little 'mini-trips' out of the room, but loudly announce "Mommy will be right back". And then go to the bathroom, go get yourself a drink, take a load of laundry upstairs, whatever. And then come back and reassure her: "See, mommy came right back! Here I am!" Do this often and pretty soon, although she will miss you, she will learn that you're not abandoning her forever and that yes, you do come back.