Seeing my mom sober for the first time

Going to the beach and my mom will be there this week. I've been sober almost a month and have been smoking weed with or around my mom every time I've seen her for the last decade. I know she has a weed pen in her RV and it's already eating me alive a little. I want to be strong and I find myself keep having these little peeks of sneaking in there and taking a drag bc "what's one little drag". I know it'll just ruin everything and I want to totally shut those thoughts out but they are so insidious. Words of strength and encouragement please.