Just follow your meal plan for the rest of the day and shake it off. Lesson learned, I made the same mistake during my P1 time too. Its definitely a learning curve. Save the PB2 for Phase 3, it will still be there!
I would just eat your normal phase 1 dinner. You feel bad enough, no need to punish yourself by starving as well. You made a mistake, now you know. Tomorrow's a new day