One day at a time is the best you can do. Mondays are crap days to start.
For some, it works better by not thinking you are going on a diet. Oh no, you are just eating healthily today. That's it, just today, just hang in there. Just one day. (Thursday)
(Friday) you've done it once, so maybe another day. Just today, only today, tomorrow you can eat gallons of chocolate, but just not today.
(Saturday) Tomorrow you can eat all the food you crave, but today, just today, only - 12 hours, if so -- just healthy food. Come on, just today, only one day
and repeat.
It won't be enough, do seek help, but just try to do it one day at a time. Pack your freezer with healthy food, super quick to defrost. Pack your fridge with things ready to eat (raw carrot to munch on). Do your shopping online, be strict. You really can't live without chocolate? Just sprinkle some on rice cakes. Plan your diet based on what YOU like, use coco powder on apples for ex, there's always a way.
You need to find the right group, the right exercise, something that will make you click
Good luck, you are trying to change for your children, you will. Of course you can change, everybody can. Just one day at a time. I hope your GP can be more helpful, but you'll get there.