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'Teen Mom 2' season 4 preview teases domestic violence and drugs

"Teen Mom 2" returns Feb. 18 ... with a cauldron full of hot mess.

The preview for the fourth season opens with a shocking scene of domestic violence. What's most surprising is that the attacker is Kailyn Lowry, the "responsible" "Teen Mom" star, beating on her new boyfriend (now husband) Javi.

But Javi isn't Kailyn's only casualty. After complaining that her ex, Jo, "put his hands on" her, she punches her baby daddy in the face.

But wait, there's more! Jenelle, who like original "Teen Mom" Amber Portwood has been arrested for violent confrontations, is seen tossing a suitcase at who appears to be new BF Gary Head's face and shoving him. She in turn complains, "I have bruises all over my body."

In more terrible news, Jenelle reunites with her bad-boy ex Kieffer, who places an emergency call because she's "high on morphine."

Chelsea predictably hooks up again with baby daddy Adam -- without using birth control. Sigh. Is this before or after he serves her court papers and shows off his new girlfriend?  

Meanwhile, Leah continues to vacillate between her devoted fiancé, Jeremy, and her ex-husband, Corey.

There is one bright spot amid all this violence, misery and heartbreak: Leah and Corey's daughter, Ali, who suffers from a neurological disorder, walks on her own for the first time! Tears.

"Teen Mom 2" returns Monday, Feb. 18 at 10 p.m. on MTV. Will you watch? Tell us on our Facebook page!

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