OP, don't focus on how 'impossible' it is because you have 'already' bunged and snacked etc etc.
Get rid of the stuff. Give it away or bin it.
Then get yourself set up with food that you enjoy, but that is healthy and filling.
If you have a lot to lose then slow and steady is best, I think. You can make healthy eating part of your lifestyle and enjoy it, rather than 'dieting'.
The first week is the hardest because you are used to grabbing biscuits, toast, whatever.
But it only takes a few days to get out of the habit.
Then, each achievement, each pound lost, will give you the motivation for the next one. And your appetite for portion size naturally shrinks.
Honestly, I took it so easy, losing roughly a pound a week since May, but it makes such a difference.
Healthy food, reasonable portions. No snacks, unless healthy / plant based. Enjoy what you eat - food is not your enemy.