I gave my ex boyfriend head today..?

Okay so I'm currently going out with some one. Today I saw my ex and I don't know what really happened. He hugged me and looked at me with that "let's have " look and then I remember going out of the store with him and we got in his truck and we had & we talked and kissed and stuff. We came very close to having but he said he didn't want to get his truck dirty and then he gave me a hickey. I don't know what to do. It was alot of fun, but I feel bad. I forgot to get my underwear from his truck too. How am I going to go around my boyfriend with a hickey, and no panties + smell + I smell like my ex (he smells good though) because my boyfriend wants to meet me for dinner and well I was all ready, but now I look a mess.. with my low cut shirt on, which reveals the hickey. What should I do?