'Teen Mom' Amber Portwood Accused of Harassing Ex's New GirlfriendMTV's cameras may be finished filming the tumultuous relationship between 'Teen Mom' stars Amber Portwood and Gary Shirley, but the drama is far from over for the young parents.

Portwood is being accused of harassment by Shirley's new girlfriend, Ashley, who is allegedly filing a formal complaint against Portwood for her threatening behavior.

A source tells RadarOnline.com, "Amber kept calling and harassing Ashley, asking her to 'meet up' so she could 'beat her a**.'"

Portwood, who has lost and regained custody of her 2-year-old daughter, Leah, over the past year, may be looking at a host of new charges in addition to the felony and misdemeanors she was slapped with in November relating to an assault on Shirley captured by MTV cameras.