I think with any addiction, you have to wholeheartedly want to stop, choose to stop and take responsibility for that choice. You ultimately have control over your actions and the addiction doesn't have control over you.
Might help not to think "right this is my last one" but to think "I'm not going to have any more as of now...
Nicotine replacement does make sense, because its the nicotine that you're addicted to, but it isn't really harmful in itself, so it makes perfect sense to take away the harmful part of the addiction, and to wean yourself off the addiction to the non harmful element to make it easier for your body and mind to cope with.