Welcome to 3FC!
I'm so sorry for your loss
Every day is a good day to start. And
today is actually the always the BEST day to start.
You know what works? Watching your food intake, and moving more.
Eating fewer calories than you spend. (Calories in vs calories out) It takes time, patience, persistence... but it's well worth it. If you take a look down at the Maintainer's area you'll see that they're still here. Being mindful, moving more, eating healthfully. They all got there in slightly different ways, but they're there now. And we're all here... supporting each other through the thick and thin. We want to see every member (including ourselves) reach our goals.
Make a food plan. It doesn't have to be complicated. It could be as simple as figuring out what your daily calories should be and then sticking to the number. It can be as simple as eating the same foods, but cutting all the portions in half. It can be as simple as cutting out all drinks except for water, and making sure to eat five veg and fruits a day.
The only thing that matters is that you start. It can begin small. Then build it up over time.
You're absolutely right. You can do this.