Self destructive behaviour

I generally am healthy and eat right/exercise, but when I feel overwhelmed, I drink too much and smoke cigarettes. I do this in secret in my garden late at night. I am so ashamed of the behaviour and worried about my health that it is a constant worry. I am so tired of promising myself I will stop this behaviour only to find myself convincing myself that “just one more time,” over and over again. I smoke a few cigarettes and then throw away the pack and the expense is so crazy and stupid. If I go away, or people are staying with me I am able to not indulge in this. I know I am buffering as this behaviour has been going on since my Dad died- years ago and I think I am trying to feel less lonely, less overwhelmed so need to take myself out of being “responsible” and my reality for a few hours. I am a solo parent. I HAVE to stop this. I just don’t know how to stop and convince myself NOT go to the store in that moment. All the arguments, my kids, my health, the expense etc, seem not to matter at that moment. I am highly functioning and would not consider myself an alcoholic, but have to stop this behaviour all it’s repercussions and move on.