What is the worst thing you've done in your life that you'll never forget?

I've done so many "bad" decisions in my life all of which I cannot forget. The worst so far is when I agreed to an "arrange" marriage. Yeah, he was my boyfriend, but I never had the opportunity to know him, besides, I never wanted to marry at 21, Mama and I talked a lot about it and I've decided to settle at 26. But well, the marriage was my Dad's decision and I went for it (with a fight). Now, I'm 27, living alone and have been separated for 4 years. All of my most recent bad decisions and blunders just branched out because of that major and worst decision of my life...