Invited to a Party

I'm invited to a party tomorrow for my friend Len. I want to go, but I don't. I'm a bit socially awkward and usually grumpy, haha. And I don't know if I know many of his friends. Plus, I hope it's not a big party because big parties freak me out. I've never been a party person. I don't know. I mean if I can always ask Ethan (my brother) to get me or something if It's too much, but... eh.... ehh....