You really have come to the right place. You CAN do it and we want to help you succeed. I've found I had to do things one at a time. I never succeeded when I tried to pick up a new diet all at once - it was too shocking for my mental processes, I guess.
I get the detachment from the rest of the world. Embarrassment is really tough. So, don't start out there. There is so much you can do at home. Start small.
This week stand up at every commercial. While you are sitting, raise your feet off the floor. When you walk through a doorway, reach for the top of the door frame. When you walk around the house, lift your knees higher and march.
Just writing down the food you eat will change your eating habits - been proven over and over. No one else needs to read your food journal, so you can be honest. Not just what you eat, but how much. Even when I'm bingeing on my chocolate [I'm struggling with chocolate badly], I write down how much.
When you think you are alone, come here. We'll talk to you. We'll commiserate. We'll cheer every success you have no matter how small.
There are probably some teams on this site that fit your specific challenges. In case you haven't found them, click Community from the menu at the top of the screen and then click SparkTeams.
Those who think they have no time for a healthy lifestyle will sooner or later will have to find time for illness.