Looking for advice on how to break pattern of quitting

Hello! I just signed up for the life coach school this week. I feel like I am ready to make a positive change in my life. I am just scared because I have tried over and over again to stop buffering and I do well for a few weeks but once something stresses me out I lose sight of my goals and succumb to over eating and over drinking. I have repeated this pattern for years. I want to break though. My current circumstance is that I work 3am to 12pm. My husband works 2pm to 11pm. We have a 6 year old boy and 4 year old girl that we take care of by ourselves 100%. I started the 3am shift about two months ago and feel like I am slowly adjusting. My problem is that when I am tired and overwhelmed (which is every day) I tend to shut down emotionally. I reach for extra food, drink, and end up feeling guilty. I feel like I have two modes, where I am committed and then the opposite during the afternoon. I will need to start homeschooling as well in the next few weeks. I really want to take charge of my thought process so I can be okay with the feelings of loneliness, stress, and sadness. Can you please offer me advice on how I can stick with the program even when I resist myself? Is there a specific video or book I can read to help? Thank you so much for taking the time to read this and respond. I am truly grateful for this service.