Selena Fires Nasty Insults At Mom Mandy In Explosive Fight Over Justin

Selena Gomez's rocky relationship with mom Mandy Teefey was on the mend recently – until the 25-year-old pop star opted to spend New Year's Eve in Mexico with boyfriend Justin Bieber instead of with her family. Now, the mother-daughter duo "have been going back and forth with each other over Justin, and Selena doesn't want to hear it anymore from her," a source close to Gomez told RadarOnline.com exclusively.

"So after Mandy came for her once more, Selena hit below the belt with a nasty insult over her failed relationship with Selena's father. That was the last straw."

According to the insider, "Selena and Mandy are not on talking terms right now."

The pair went so far as to unfollow each other on social media.

As RadarOnline.com previously reported, Gomez and Bieber rekindled their relationship recently after more than a year apart.

Since then, the lovebirds have been inseparable and are already talking about getting married.

The Full History: Every Selena Gomez & Justin Bieber Break Up & Make Up!

"At this point, Selena is starting not to care what her mother thinks, or what anyone thinks for that matter. She is going to do what she is going to do and there is nothing and no one that will make her walk away from Justin at this point," the insider added.