What can I do for my kitten?

I just got two kittens a few weeks ago, and two days ago I had a birthday party. I wanted to keep the kittens in my bedroom, but one of my friends kept bothering me about letting them out. I did, and it was such a dumb idea, because she promptly picked one up and held it with one hand. She didn't let it down for the entire party, even though it cried and scratched and bit. I tried to take it from her and put it down, but she picked it right back up and got mad at me. I know I should have just told her not to hold it so long, but I didn't. Now, the kitten won't come out from under the bed for anyone but me. I feel absolutely terrible, and I'm never inviting the friend over again. Is there anything I could do to make the cat not so afraid?