Under Pressure: Rehab Alum Leah Messer Can Keep Custody Of Daughters— IF She Behaves!

Leah Messer is out of rehab and reunited with her three daughters— but she could lose it all in an instant.

According to Life & Style, the troubled Teen Mom 2 star, 23, who as RadarOnline.com exclusively revealed, got help for prescription drug abuse earlier this summer, will be able to keep custody of her kids as long as she stays on the right path.

"So far, Leah's been on good behavior and things are running smoothly with her and the kids," a source tells the magazine.

"But if her behavior raises any red flags," the insider adds, her ex-husband and baby daddies Corey Simms, 25, and Jeremy Calvert, 27, will take action.

It seems as though Simms, the father of Messer's 5-year-old twin girls Ali and Aleeah, has had a change of heart. In June, the proud pop was planning to fight for full custody of his daughters as soon as Messer checked out of treatment, RadarOnline.com exclusively reported.

"With her drug and emotional issues, Corey doesn't think Leah is in any shape to be a good mother right now," an insider explained to RadarOnline.com. "He will stop at nothing to make sure his girls are in safe hands."

Since her rehab release, sources say the MTV reality queen has been spending quality time with her daughters, new older boyfriend T.R. Dues, 32, and his sons.