My husband has been the same way. Having a little treat turned into a whole week of treats. He's gotten better but still definitely has a tendency to go that direction. If we do buy a treat now and then, we buy a small portion of it, definitely not a sharing size, and that's it. When it's gone, it's gone.I don't agree. Letting myself have any junk food just opens the door for more and more. It's important to not fall into cycles of binging and then cutting it out entirely, but, as a goal I prefer to set the bar higher.
We're lucky in the sense that we don't have the grocery store very close by so we food shop every 2 weeks or so. I don't know if that's an option for you... literally going to the grocery store less frequently.