PLEASE HEEEEELP , URGENT ?

Okay so I'm not supposed to have a Facebook and I do. I've been caught before but I made an excuse and got out of it. Now there's no getting out of it. My brother told me my grandparents found it and they're gona talk to me about it. I need to know how to calm them down, make them less angry, and not hit me. They've never hit me before but there has been one time when my grandfather almost did. They're gona be furious about the Facebook account. I need help.. how can I calm them down? Get in less trouble and not get hit ?