Hey there,
I can relate to your strife, and certainly remember well those feelings.
It may be things will get worse before they get better, but they will get better.
Educate yourself about addiction (Start at the top of this page) and as you will always be advised here, try Al-Anon. This will help you and may influence your wifes own view of herself and her addiction.
When you say "I can't tell anybody" keep in mind that denial and secrecy are the main continuation mechanism of addiction.
We are here for you...