Yah, I drink a diet caffeine-free beverage too... it's called water
Just kidding, I feel your pain. I have been addicted to Pepsi for the last 16 years. I was drinking at least three cans a day, usually more like 5 or 6 a day. I pretty much went cold turkey in May of this year. So far I'm doing well. No more headaches. I do "treat" myself to one every two weeks or so. My fear is that I will start back one day and will gain back the 14 pounds I have worked so hard to lose.
FWIW, I tried the diet stuff for a couple of days and then realized that it was pointless to drink that when water is so much healthier.