I agree with Aquaknight.
It's going to take some time, but it can be brought back. You'll need excellent water parameters and proper lighting to start. I wouldn't bake it under very intense lighting right away because this could damage it. What type of lighting do you have?
Also, try squirting some food at it while feeding your fish. The tentacles look healthy, despite the bleaching, so it should be able to catch some food that blows by.
Good luck!