Stay strong sweetie, and do whatever you need to do food-wise. I don't advise eating junk food as you'll feel rubbish, but make sure you're getting good nutritious calories somehow even if they're not through the shakes. Try the bars (even an atkins bar perhaps if the S&S ones haven't come yet), vegetable crudites and whatever protein you feel like you can manage. Although not strictly SS, M&S do precooked chicken slices in various flavours with very little carbs? I think protein is quite hard to take when you have no appetite - my fallback is little cubes of marinated tofu or adding silken tofu to the shakes if you can manage them.
And remember - if you have to play around with the plan a little or perhaps go off slightly it isn't the end of the world. This is a difficult time for you and no-one expects you to be a superhero; you have to do whatever it takes to keep yourself strong, well, and able to cope with this awful situation.