Can someone tell me anything about heroin withdrawals?

I don't really want to get into the whole backstory, but my gf/exgf (it's obviously very complicated) is a heroin addict. When I met her she had been clean for a few months, and we were together for about three. Last week she abruptly broke up with me and went on a bender. I later found out that her 'sponsor' (who, for whatever reason, was an older male; she had said it was 'alright because she's known him since she was a child') sexually assaulter her, which caused everything.

This morning she showed up at my house, looking like a mess. I was so confused until she collapsed in my arms and asked if she could stay there. I REALLY didn't want her around after everything, but she looked so pathetic. When I found out about the assault, of course, I was much more sympathetic, but I have no idea what I'm doing.

She's in my room, and just miserable. She's vomited everything possible up, I feel, and is in a lot of pain, but I think that's normal. She says she just wants to 'get it out of her system' and 'then go on with her life,' but I know she needs to get into rehab ASAP. I just don't know how to convince her, and I sure as hell don't know how to comfort her. I've never been around any drugs before (I can't stress this enough. I've never even been around pot).

I tried threatening to call her parents, but she got extremely upset and threatened to leave and never come back. Her parents are very well off, financially, and can definitely afford for her to go into treatment, BTW.

She's only 20 years old, and extremely intelligent and bright. I feel like she thinks she's 'smarter' than the drugs and she'll be fine. I mean, I know heroin is some serious shit (I've SEEN Requiem for a Dream AND Trainspotting... -_-), and I doubt she can just 'wait out' these withdrawals. I really do care about her and HATE seeing her in pain... I just need some advice and have no idea who else to ask.