I'm going thru the same thing as you right now and it does hurt but you have to look at the reasons why it got to this point in the first place. I just keep reminding myself of these things and that keeps me on track. It's difficult to kick the habit and when the breakup is fresh and it seems like the right thing to do, those feelings wear off and you just want your old "normal" back. Don't fall back into that rut and just keep marching forward.