The best thing to do is jump right back in. If you feel cravings (or think you will), do P1 until they go away. Try to think about why you "caved"...did you not plan for the event? What could you do next time to avoid this? When there's a special event like that, I try to find a restaurant that we can go to that is on his list of places he really likes where I can also eat. If I make him a decadent cake/dessert, I make something equally decadent (but SBD-safe) for me. It helps if we celebrate on the night that I have my weekly chocolate.
Hope that you don't have any cravings to deal with and that they pass quickly if you do.