My boyfriend's dad walked in on us, advice?

Oh gosh. I feel like poo. My boyfriends dad wasn't home and he was about to take me home from our friend's house so we stopped in to have sex. We had been at it for a while and I was riding him on his couch. He jumped up hearing dump trucks (him and his dad own a diesel station) I told him it was just a truck his dads in his car. So he sits back down and I continue. Then we hear keys rattle and the door open. I fly off and grab a blanket to cover up. Before he comes in the house from the front porch my boyfriend say woah don't come in here. His dad says sorry I'll go next door, can y'all put up the yogurt once you're done? His dad is super Christian. But when we went inside the shop he was smiling and laughing. He didn't know we were even havin sex. What do I do? I feel horrible! We're both 17. Oh god I am going to hell. But damn it is funny now.