I REALLY SCREWED UP! WHAT SHOULD I DO NOW?

if you had been having a conversation, and you were asked to leave by your friend...that is a perfect opportunity to ask for her number regardless of who is there. "hey i gotta go, but could i get your number...love to talk to you later/do something" or wutever, but sound confident, not like a chump. you just gotta go for it, worst case scenario, she says no