All good points. I posit the following refinements. You cannot go back in time and fix anything. You need to change behavior moving forward.
1. Live at or below your means.
2. Cook your own food, never pay to eat out, ever.
3. Avoid self-pity. You don't deserve to "reward" yourself if it is going to threaten your well-being. Forget about that. This is about survival.
4. Shop at ethnic groceries for basics and staples. Things like vegetables, flour (yes, learn to bake and make bread from scratch, etc.), rice, beans are much cheaper at ethnic groceries (Indian, Korean, Mexican, Chinese, etc.) than what you pay at Safeway/Kroger/Albertsons/etc.
5. Cut back on protein and increase your fiber intake (it's cheaper and mostly healthier).
6. All of the bland, mundane, boring food can be depressing. Add vinegar, oil, Italian-style seasonings purchased in bags from the ethnic market. Splurge on balsamic vinegar if you really want something to supercharge your taste buds. Be open-minded to new types of foods as steak, prime rib and pork fillet should be avoided due to cost.
7. Buy a pressure cooker, you'll be amazed what you can do with cheap cuts of meat and vegetables.
8. Cook with the intent of eating left-overs. No better way to leverage your food budget.
9. Drink water. Sounds simple but it is cheaper than soft drinks, alcohol and juices.
10. Lastly, at the big grocery stores focus on their loss leaders and avoid buying routine goods there.