i always set mine to the most annoying and loudest ringing sound one that's already on my cell. that way when it rings i never miss the call. and cause i use it as an alarm clock to wake me up in the morning
ahahahahaha, that really sucks the big one man. don't know that you can do anything other than completely ignore her or tell her the truth. or you could make something up like somebody stole your msn password, i don't know.