I need willpower today!

So today were celebrating my grandmothers 97th birthday. lunch is home made chicken fried steak, potatoes and gravy, white diner rolls, chocolate cake with chocolate frosting and of course I cream. I broughty own small salad and a sweet potato to keep from eating everything in sight. I did eat a 1/2 piece of meat with a dab of gravy. I'd normally feel full right now but knowing there's a lot of good food left I want to eat it! the cake looks deliciously fattening. I've passed it up so far but Idk how much longer I can look at it without eating it. need help!