Diet Caffine to Diet Caffine Free to Zero Pop

So I'm a huge pop drinker and I drink diet pop. I haven't had regular soda since January and it has helped a little. The problem is that I'm a caffine addict. I started drinking Diet Pepsi Max and after 2 of those I went 1 day without having one and it about killed me. After I took one sip of it the next day, I was fine. It's very pathetic but I need help to get off the caffine kick. After I do that, then I can focus on going from caffine free pop to no pop at all. That's my ultimate goal. Any suggestions on how to do this?