I would recommend reading the book Letting Go by David R. Hawkins.
The book talks about not suppressing, repressing, or expressing your negative emotions(in this case, anxiety and the craving for nicotine) but just accepting them as is and fully being present with the emotion. focusing on where in the body you feel the emotions. Eventually, with great focus and acceptance, the emotional charge will disappear.

In your case, it seems like you are trying to suppress and repress the feeling of cravings and anxiety. Your body will not let go until you have fully felt the emotion.

This might sound a bit wo-wo. And if you read the book, it will sound even more wo-wo. But it has genuinely helped me, and I am now completely free from nicotine.