I started my period at my boyfriend's place with a bunch of friends. What to do!?

So, I was at my boyfriend's house and I was totally not expecting my stupid period, but i got it. It's always really heavy the first day, so you can only imagine how I felt when blood went through my pants onto the couch that i was laying on with my head on his lap. I saw it and started tensing up and like freaking out and like leaning over so he couldn't see it. But, he did, and was like "Ummm, do you need help with that?" I was like "Errr no, ehh... just a nose bleed." Then all of our friends started cracking up because apparently they saw right through my lie. Anyway, I'm still mortified, what should I do!?