I [20M] am addicted to drugs and don't know how to tell my SO [21F] that I need help detoxing (possible triggers?)

Please tell me if this isn't the correct place to post this, I was a little unsure.

Just last year my girlfriend (who was also a friend of my current girlfriend) passed away from a drug overdose. Fast forward a year and after months of me being clean after what had happened, a friend of mine quit drugs and trusted that I would dispose of a bottle of 350 oxy's. (If you're a drug addict, you know how hard it is to just throw it away) Being a recovering drug addict, of course it was easy for me to relapse, I just won the jackpot in my mind! So I've been taking anywhere from 8-10 pills a day. I'm still just under 80mg a day but I wake up with horrible aches and sweats every day and it's to the point I think I might die if I don't quit. My health is very quickly declining. I had to get an ekg last minute at the doctors last week because they're concerned I've had a heart attack.

My girlfriend has been the biggest part of my life this passed year. We started dating July of last year. She's helped me tremendously with the loss of my girlfriend and I've helped her with the loss of her friend. She's the best thing that's ever happened to me and I want to spend the rest of my life with her but I need her help to get clean. She has no idea I've been on drugs. Right now we're living apart while our home undergoes renovations. So she's been an hour away at her moms and I see her maybe once or twice a week. We've had conversations in the passed about me using drugs and she had told me if I ever decide to start up again, she couldn't be with me. I know I've already betrayed her trust but I need to find a way to make her understand I'm seriously sick and I need her help. I know I can get clean once I get through the detox. How do I break the news to her?

tl;dr: girlfriend super against drug use, I've been using, need way to tell her so she understands I'm sick and need her help