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48 Hours Preview: A survivor of teen dating violence got out in time, and now helps others do the same

Teen dating violence: A survivor shares her story

(CBS) - Looking back, Brittny Henderson knows she was lucky. Unlike too many other young victims of dating violence, Brittny broke off her relationship with her abusive boyfriend before she really got hurt.

Watch a sneak peek of 48 Hours: Loved to Death

"It all happened so slowly," says Brittny, now 23, of the increasingly aggressive and controlling behavior her once goofy, fun boyfriend started exhibiting. At first, she says, he kept her from outings with friends. And then he shoved her against a wall - by the neck.

"My friends saw me changing, but they were just as uneducated as I was," says Brittny, who is studying to be a pharamacist in Austin.

WATCH: Teen advocates on dating abuse, warning signs

What Brittny and her friends didn't know then - and what she is now spreading the word about by speaking on the subject in schools - is the fact that according to the Centers for Disease Control, each year 1.5 million American high school students endure physical violence from a person they are dating.

On Saturday night, 48 Hours is airing a special program on dating violence, focusing on the case of Lauren Astley, whose boyfriend Nate Fujita was accused of murdering her after their break-up.