I'm going to say no to helping out a friend.
They are you friend! Why wouldn't you help them?
He ignored me at a party he brought me to.
It's impolite not to help out a friend. I understand being frustrated that he ignored you, but retaliating won't make him want to treat you better in the future.
He was a jerk to me so why should I help him?
Because even if he was a jerk, he's still your friend. Friends make mistakes and it's important to be able to forgive them. Doing something to try to retaliate against him because you are mad will just make your friendship worse.