What do I do?? thankss..?

I try to keep my calories under 600 everyday. Yesterday I only had 100 calories period. I felt great about it. I had not eaten anything all day today until dinner which I probably could have gotten away with skipping...but I didn't. I had 1 cup of pasta, 1/8 of garlic bread, and 2 pop tarts. All adding up to 930 calories! I went to exercise it off, but still felt WAY guilty, so I tried puking. I couldn't. How can I rid this guilt?