I've been trying to lose weight but had a full day of over eating?

I'm just feeling a little worried. I have gained weight and just last Friday I started going to the gym and really eating well... however, today I ate heaps of food, including spaghetti marinara, bread, chocolate ice cream, lollies and nachos on top of breakfast... I feel horrible. Should I just eat less tomorrow? It will balance it out right? Thanks for your help.