manipulative

My friend is making terrible choices: how can I help?

Marie asks:

My best friend thinks its safe to have unprotected sex. She's sixteen (and has been for six months) and her boyfriend is fourteen (and will be for another three months). He thinks she's on the pill, so he doesn't ask her that they use a condom. Even though both of them were virgins, she was his first girlfriend while she had been "messing around" with guys as old as thirty four when she was as young as twelve. Her boyfriend is best friends with my boyfriend, and she is my best friend. Neither my beloved or I want to see this happen, but she acts like it's no big deal, and he yells every time we try to ask about it. She tells me I don't know what I'm talking about, since I'm a virgin and so is my boy -- and we intend to stay that way until we're in a truly committed relationship -- and says to just quit bothering her about it. If I didn't know for a fact that my best friend WANTED to have her boyfriends baby -- and soon -- I wouldn't stress nearly as much as I am currently. I don't know what to do, and was wondering if you could give me any advice... anything is helpful, I know she isn't ready for a kid and wish I could find a tactful way to convince her that there is no safe kind of unprotected sex. I've already showed her Scarleteen, and she brushed it off... so I'm out of ideas. Thanks much!