I was in the same situation years ago except it was me that was on the other end with loved ones chasing me and trying to help me get clean. The unfortunate reality is nothing you do or say to an addict will do any good until they decide to get clean and that usually isn’t until they hit rock bottom. I don’t know your situation exactly and I don’t want to come off like a dick but if she is choosing drugs over you you might want to step back and reevaluate the situation. Tough love is what worked for me meaning that I no longer could crash or get cash from my family and non drug related friends. It’s a hard thing to do but when an addict loses the family enablers its a big step closer to getting their head fixed.
Like I said I don’t know your exact situation but I’m a real expert when it comes to drug addiction, rehab and manipulation and if you choose to hang in there for the long haul be prepared for a bad ride on an emotional roller coaster . My advice, check out the show (if you haven’t already) called “intervention” on the A&E channel. The website is http://www.aetv.com/intervention/ and they have some good tips and a forum for discussions with people like yourself going through similar situations.
Your a good guy for trying to help her and thats to be commended but don’t ruin your life trying to fix hers. Lastly, if you are a spiritual guy (or not for that matter), lift her up with prayer all through the day. It worked wonders on me.