it's definitely not just in your mind if you are going through withdrawals. sounds like you have developed a physical dependence, whether you are addicted or not is determined by your success in quiting. if you cannot stop and stay away from any mind altering substances, then by definition you are addicted.

if your withdrawal symptoms become worse, you should go to the nearest detox or ER. they can help you feel better on your way off, and can suggest ways to stay stopped.

consider attending a few 12 step meetings to understand the disease of addiction. many people get clean with the help of support groups.