Hey Snazza, Welcome to the site.
First off, big hugs. I know with far too much experience how that scared sad nervous disappointed crying feels.
But I also know what it is like to have wasted my 20's being overweight and ashamed and hiding from the world. My strongest word of advice to you is to NOT waste those 20's hiding in shame and self-hatred.
1. Get exercising. Cheapest way to do that is to walk. There's a stack of exercises on here that you can do which Ray has prepared, that cost you nothing, you can do them outside in your garden or in the park or in your lounge room. Just 30 minutes a day will help you take permanent steps to a healthier body. You will also begin to feel better about yourself.
2. Follow a structured, well balanced and proven eating program, like Weight Watchers. (If you can't afford to go to meetings, buy their magazine & follow the food plan in that. It's pretty self-explanatory). Don't fall into the trap I did of not knowing what good nutrition was (until my 30's...argh!), of fad diets, pills, potions and money-sucking things that do not work. You will go crazy if you follow that kind of thinking - there is NO MAGIC SOLUTION.
3. Don't give up. By doing good each day, you will come closer to your goals. Stick to a plan, don't falter. If you lapse, get right back up and onto it - if you end up eating stuff you wish you hadn't, don't beat yourself up, get off your bum & go for a walk. The worst thing you can do is fall into the self-loathing, negativity trap that so many people do. It ends up doing nothing but harm to yourself.
4. Find something each day that you are proud of. Gather your cheerleaders. They will help you reach your goal. Get a whiteboard on your fridge & write down the things you are proud of. Lost a kilo? Write it down! In big bold numbers!
I hope some of this helps. It's the basics of what I've learned. Good luck. Ask all the questions you need to.
Kaz x