I feel your pain. FH has an idiot like this in his life, except that he went on like a handful of dates with her before he met me. She keeps finding reasons to get back into his life....most recently it was she was planning a birthday party for one of his fraternity brothers and claimed to want his help.
Some women are just so jealous and pathetic and desperate. Sad thing is, men usually don't pick up on that. Be glad he didn't pick up the phone, but he really should just tell this girl to give it up already.