I ate too much and now im terrified what should i do?!?

Okay, so this morning I made a red velvet cake for my parents and their anniversary and my little brother ate a lot off of the bottom and so I ate the rest at to bottom to even it out and afterwards I felt so incredibly horrible about it. I have been excercising rigorously every day because i am trying really hard to lose 30 pounds I HAVE TO LOSE 30 POUNDS and recently I haven't been able to finish my workout dvds well which is really weird because they should be getting easier! I haven't eaten anything else all day because I'm scared ill gain weight and I'm only going to eat my broccoli for dinner. Am I okay? I did a morning workout and I exercised for about an hour later but I'm still scared.