Welcome, Cathy.
My mom was about as addicted to cigs as anyone can be. She's had 2 heart attacks already. The first time she quit, she made it for 9 months. But the terrible depression made her start again. She quit after each of her 2 heart attacks, only to face panic attacks, weight gain, and more depression.
But when she was diagnosed with sclc, she was having problems with coughing up blood. The possibility of coughing and having a fatal bleeding episode (a 50% likelyhood, she was told) was enough to make her quit for good. Paxil is her new best friend - and at a high dosage.
Bottom line? It's really, really hard for some people to quit. Make sure you get the support you need - and that means medications. Nicotine is a powerful, highly addictive drug. You CAN do it, but make sure your doctors give you all the help you need.