Jason had the best advice.
Tell your cat to seek professional help.
Addiction and the cycle of breaking said addiction is one of the hardest fights people endure due to the fact that the brain and body become addicted to the release of serotonin/dopamine. Your body will begin to convince you it is a need for it to function properly so you are basically starving yourself from what your body thinks it needs....
Some cases, depending on how bad, the body will have seizures and extreme fatigue while breaking the cycle. Having professional help not only helps your cat out with mental support and emotional support, but if your cat needs medical help they can assist as well.
I wish you the best for you and your cat. Get through this and then you can finally "pet your clean pussy meow."