What happens after I file...?

It depends on where you live. Depending on the amount of crime in that area. The police might take it seriously or just tell you to change your number. If it is taken seriously, they'll probably take out a TRO (temporary restraining order) until such time you prove that a restraining order is justified. Or they might skip the TRO and have you wait and justify it. If your worried she might harm you that comes into play to. But they won't arrest her until she breaks the restraining order.