If you really must eat, you can choose a meal which will allow you to stay in ketosis. Meals which would do this would be steamed/grilled chicken or fish with salad, but no dressings. This would mean that you could have the meal and continue with TFR the following day, hopefully without any damage. By doing this though, you will be unable to drink alcohol as it can be very dangerous whilst in ketosis.
Clair x