Welcome.
No advice for the guilt. But wanted to really suggest SMART recovery. Its chuck full of tools you will use for the rest of your life.
Check out their website. They also have a forum.
Actually, I do have a small suggestion, and that is to focus on now. As one who lost a well paid job and his family due to alcohol and drug use, I know the feelings of regret and guilt all too well.
It's a sickening feeling. Almost palatable. Obviously it's strong enough to motivate you to ask for help. Your post, as just about every "I'm new here" post, sounds desperate. Normally, it's a desperate plea for help with addiction.
Your post however, is emotional as it relates to the ultimatum you placed on yourself. Which, obviously does seem to have some effect. At least in the short term. At the end of the day though, Dee, as usual, is right. Ultimatums don't work. SMART recovery will.
And one of the many tools I learned through SMART, is to focus on now. What's done is done. When the thought enters the mind, don't allow yourself to think of it. Instead, focus only on your breath. Take three deep and slow breaths with your eyes closed. Open your eyes, and take note of your surroundings. Look at the sky, if possible, so you get a sense of the bigger picture.
Do that every time that thought enters the mind, and it'll go away on its own. This technique helped me overcome my guilt.