Welcome to SR!! As ((Dee)) mentioned, we have the substance abuse forum and there are a LOT of people there who have/or are still going through opiate withdrawals.
I abused them, a LOT, but for some reason I never had withdrawals and then turned to crack.
From what I've read, it's like a really bad case of the flu...restless legs, diarrhea, sniffles and aching all over. Not really sure you'll be able to work through that. Seems it starts getting better in about 7 days (again, from what I read).
Suggestions I've read are to stock up on sports drinks (gatorade/powerade type stuff that has electrolytes in it), get some immodium, take lots of hot baths for the restless legs, and be prepared that you're going to get very little sleep for a while.
However, I know of numerous people who have done it. I also think that the support of other recovering addicts is crucial. My recovery was enhanced by people here who were addicted to all kinds of things, but they each taught me something.
There are numerous recovery programs available and I think they're posted in the stickies (posts at the top of the substance abuse forum).
The good news? This can be the last time you have to go through it. May want to journal what you're going through, so you have it to read back when the using thoughts come back.
Hugs and prayers,
Amy