Louis Tomlinson’s ex, Briana Jungwirth, seems to have an issue with the new lady in his life.

The L.A.-based stylist slammed Tomlinson's girlfriend, actress Danielle Campbell, on Twitter on Wednesday writing: "You can pretend all you want but you will NEVER be my baby son's mother."

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The shady tweet was a likely in reaction to photographs of Campbell spending time with the One Direction singer and Freddie, his 5-month-old son with Jungwirth, over the weekend.

However, Jungwirth's post got mixed reviews from One Directioners. Some showed support, and others advised her to keep family business off of social media.

Jungwirth and Tomlinson, both 24, welcomed Freddie in January, but broke up before his birth. The British pop star began dating Campbell, 21, last December.

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Unfortunately, co-parenting hasn’t exactly been smooth sailing. Tomlinson is currently seeking joint custody of Freddie, and recently accused paparazzi and media outlets of invading his son's privacy.

"The persistent and increasing levels of paparazzi and media intrusions into Freddie's life of late are not only posing potential security issues but are also crucially invading the privacy to which Freddie is undoubtedly entitled as a child," reads a letter from Tomlinson's rep obtained by ET. "The levels of paparazzi attention on Freddie are intolerable and completely unjustifiable."

Find out what Tomlinson wants Freddie's first words to be in the video below.