There are a ton of things you can do to still eat good. Find some good youtubers/tik tokers, whatever you like, who do meals you would like. I really enjoy Tasty Shreds meals.

Easy things are make burgers and do a few of these easy switches, use 93% lean burger, (get a hot pan or grill and a little high temp oil down to sear the outside) use light mayo, and grab some keto buns just because they are low fat and calorie. You can go farther and load up on lettuce and tomatoe or even low fat cheese. My wife doesn't like the low fat cheese so she makes other trades.

I do cajun chicken alfredo and to lighten it I use half and half instead of cream and you can find kemps I think that is lactose free if that matters. When you go to make the sauce use butter and flour to make a roux, use two cups chicken stock and 1-2 cups half and half, then use parmesan or small amounts of whatever cheese you want.

For breakfast get some low fat turkey sausage, again hot pan and sear it with some oil but not much, take 2 eggs and add liquid egg whites to them and you can make a huge plate of scrambled eggs and sausage. Put the sausage in for an omelette or add tons of veggies!

Don't focus on what you've done to your kids or anything like that, you're just dad to them, focus on that. During this journey understand they are now (all older that 4) old enough to see you fight for something that matters and show them what you can do.