Eula325,
My path was very similar to yours. I never smoked but was a black belt ninja. My wife caught me about 3 times. Of course I promised to her that I would quit. But I never personally accepted the fact that I was going to actually do it. First step is to actually want to. The next step is difficult at best which is admitting to her that you lied which is going to break her heart and trust. But the honest truth is this...If you don't come clean with her and she finds out on her own, then it's going to be worse. Me and my wife have grown closer because I admitted that I had a problem. I showed her all my hiding places and came clean. I involved her in my process and what I was going through. I asked for her love, support, help and forgiveness. I showed her this group and let her read the posts that I was making. In other words, it wasn't my problem, it was our problem. This gives you several things. First it gives you another accountability partner. Second, it shows that you really want to quit. Third it shows that you want to rebuild trust. Remember that telling her "Believe me" won't work since you have already shown that she can't. You have to show her. Fourth, this is going to show that you really don't want to hide anymore secrets from her and how much you value her love. You should not have ANY secrets in marriage. NONE what so ever. Later after you get to post your HOF speech, reflect back with her on where you were, the pain you had, how much you appreciate her help and how much more you love her because she stayed with you and walked the road with you. By no means is this going to be easy and there will probably be tears. But part of marriage is facing each other and baring your soul. For better for worse. Make this the worst and you will be fine.
As to an actual approach...I didn't need to find a way to bring it up since I was caught in the act (maybe my black belt wasn't so black after all). But I would suggest something like this.
Honey, I need your help. I haven't been completely honest with you about something. I have a problem and I need your help. I have a nicotine addiction and I want to quit. I love you and I want to be around for you forever. I've already joined a support group but this is going to be hard, very hard. (She's going to be crying by now) What I've been doing is not right and I have compromised your trust and I want a chance to earn it back. ---From here, you are going to have to play it by ear. But you need to give her specifics about how you ninja'd. Give her some of the details about what you are going to be going through. Read on the forum pages if you aren't aware yet. The first 10 days are going to be very hard and everyone on that is on this forum will say the same thing. Stick with it at all cost. Do what you have to to but absolutely no nicotine. Gum, sunflower seeds, paper...whatever you have to do to get through that time. (BTW, I would not recommend cinnamon oil. Read some of my post from my initial quit) It WILL get easier but understand this, you will never ever be able to say that you won't be tempted again. It would be a good idea to come clean with your dentist and talk to your girl about what he says. She is going to want to know that you don't have a hidden problem and you should too. We have lost some people in this group and this is a serious thing. Anything you can do to involve her in the process is going to be a good thing in the long run. Whatever you do, don't use nicotine as an excuse for your moodiness when it happens. Own it, accept it and ask for forgiveness often. She's going to need to hear that a bunch. You are going to have to take a couple of blows because of this but by doing this with her, your marriage will be stronger.
Brother, you can do this! Day by day...One day at a time. Post and post often! You have found a great support team and everyone here want's you to be able to say "I used to dip".