Should I dump my girlfriend for this?

[!]

Somebody posted some strange stuff on my gf's wall on facebook, and I confronted her about it. She basically broke down crying and told me she was a freak in high school and had sex with a lot of guys and one time she had group sex that was video recorded. She said the only reason she told me was because she wanted to have my trust and be totally honest in our relationship. And she promised that she changed.

I'm just shocked and don't know what to do. She seems like a great girl but that is crazy baggage. The girl I'm dating was a major **** in the past.