Need some advice/support
 

I have about 8 drinks per night. I hide it from my wife. I hate the feeling of secrecy and shame, and I hate not being productive because I am in an alcoholic haze all night. At the same time, I am scared of quitting because of withdrawals. I don't know what to do. I can't tell my wife and go into an inpatient detox, she would leave me if she knew I was hiding this.

Chances are she already knows about your drinking Galumphus. As much as we like to think it's a secret, it's nearly impossible to drink that much without our spouses or significant other knowing. More likely she's simply in denial about it. And quite frankly, if you don't do something about your marriage will probably end eventually anyway.

If you fear you'l have physical withdrawals, you need to see a doctor. Doing it on your own is potentially far too dangerous without at least an initial consultation. Detox and rehab isn't inevitable, but don't rule it out as a possiblity.

Does she know you drink at all? When I was getting hammered every night I smelled like a liquor store (That was hit by a tornado).

She might actually be supportive that you are getting help. I would have a hard time believing she knows nothing of your drinking.

Well, you made the first step of admitting you have a problem.
If I were you, which I'm not, I would tell your wife. Why keep it a secret? Everyone knew I was a drunk even though I thought I was pulling the wool over their eyes.
Honesty with her would be a great start to sobriety. We're only as sick as our secrets.
Then, you could be free to address your drinking problem. With her support, hopefully.
I hope your marriage is strong. If you love and trust her, she probably feels the same about you. So maybe you think you've broken that trust. But this can be repaired.
This is just what I would do. I sincerely hope it works for you.