You are withdrawing from an extremely addictive drug.
When inhaled or ingested, nicotine bonds with receptors in our brains that trigger the release of dopamine, a feel-good hormone that is thought to be closely tied to the addictive process. Your body will react to the absence of nicotine and so will your mind, so don't worry if you feel bad and can't stop thinking about smoking. The discomforts are normal and temporary.
The key word is temporary.
It won't feel temporary while you're in the midst of it, but nicotine withdrawal will pass as long as you don't smoke.
Junkie thinking is part of nicotine withdrawal.
Or, to put it more accurately, junkie thinking is part of nicotine addiction. Once you stop smoking, you can expect that your mind will twist itself into knots trying to convince you to smoke. Put yourself on ignore and don't light up. Junkie thinking will subside with time.
Remember that smoking is responsible for how you're feeling.
It is common for new ex-smokers in the throes of nicotine withdrawal to think that quitting smoking is to blame for the pain they're in. The truth is that smoking (and the nicotine addiction that followed it) is why you're feeling so bad right now.
If you smoke, you'll be back to going through nicotine withdrawal every time you need a cigarette. If you stick with your quit, this will be the last time you have to experience nicotine withdrawal.
You gotta go through it to get through it.
There is no avoiding this part of smoking cessation. The nicotine has to leave your body. That said, there are quit aids that can ease or even eliminate the discomforts. More on that below. Think of nicotine withdrawal as a task to be completed during recovery from nicotine addiction. It doesn't take long in the grand scheme of things.