It rather depends why you invited the ex. Did you invite them before the breakup? Do you have a friendship with them independent of the relationship with your "somewhat close friend"? Do you know why other people are saying they won't come if she is there? Without this information the question is much too broad. If you add this, you can ask "how can I respond to people who tell me they don't want her to come?" or "how can I tell her I don't want her to come after all?" or some other interpersonal skills question that is not "what should I do?" —
Kate Gregory 1 min ago