Lover boy I thought she was your girlfriend and not your ex, but anyways if she wants that then kiss her until you're with someone else!
As a crab once said in the Little Mermaid 'you gotta kiss the gurllll' trust me just do it.
Okay, I wouldn't do it if I were you. This will just result in mixed emotions and the situation will be 10x harder. But I don't know if you are a teenager or an adult, so I can't say too much.