"Teen Mom 2" star Leah Messer could be in for a rude awakening at the series' next reunion show gathering.

RadarOnline reports that her ex-husband, Jeremy Calvert, is tired of being seen like the "bad guy." Supposedly, he plans on "exposing his ex-wife as a serial cheater."

A source tells the website that Calvert, 27, is more than willing to admit he has hooked up with other girls, but insists that was all after he and Messer split.

He allegedly adds that she, on the other hand, "didn't hook up with just one guy, there were tons."

Just last fall, the father of Messer's 2-year-old daughter, Adalynn, openly accused her of being intimate with ex-boyfriend Robbie Kidd. Messer vehemently denied the claims; yet, it was confirmed by Kidd.

Sources contend Calvert now has proof of several other similar instances and plans to spill the beans on the next "Teen Mom 2" reunion. Messer is now rumored to be dating 32-year-old West Virginia sports trainer T.R. Dues.

Radar has also recently reported that sources claim Messer's issues run a lot deeper than just her failed marriage.

"She had a very rough time growing up," a source told the website of the 23-year-old mother of three. "Many people, even her close friends, don't know that she dealt with a lot of pain and suffering when she was a very young girl."

It's rumored that this at least partly led Messer to the prescription painkillers she was once hooked on. Messer is now supposedly undergoing treatment at a rehab facility. The source added that in Messer's case, treatment is twofold: It will help overcome her addiction and learn to cope with all she's been through.

During last season, Messer admitted she suffers from anxiety and began taking an unnamed medication that left her foggy.

The next season of "Teen Mom 2" is set to premiere on MTV on July 8.