What are the careless decisions that can completely ruin one’s life?

Not listening to my instinct to stop a relationship. That was the wrongest decision I ever made, not listening to myself.
I was brainwashed, gas lighted, whatever correct past tense form of that word is, and abused. Assaulted regularly, even hit across the face once, physically blocked from leaving a hotel room, lied to, coerced, given severe anxiety, depression, and PTSD. And this could have all been prevented if I listened to and watched the first few red flags that popped up. The first night we slept together, after, he showered me with love saying I was the best thing in the world, wrote me a poem, and picked me flowers from his moms garden. I thought that was so sweet at the time. In retrospect, it was a huge red flag, now I know that’s called love bombing.
When his ex girlfriend talked smack about me to him and pretended to still be his friend, that was a red flag. When I had to call his sister to come pick him up because he was severely intoxicated, stumbling around my house, that was a red flag. When he got drunk again at my house and called me every offensive name in the book, that was a red flag. When he called me the next day asking to go skating and I told him, ‘no’ flat out and he asked why and manipulated and gaslit me into taking him back. I was still in my own house then. That was a red flag. There were so so many warning signs. But I had never ever met someone so manipulative in my entire life. I had never seen that kind of evil and I was totally unprepared with how to deal with. I questioned my own sanity. I questioned everything about myself. I was a shell of a woman when I finally got the courage to leave him. He absolutely ruined my life.
I became a raging alcoholic to deal with the pain and misery, because I didn’t know how to deal with my problems. I’m still recovering. I’ve been sober over a year and a half now but at what cost? I regret having ever met him. I regret after having gone home with him that night. I wish I had never talked to him again. I wish I had just got home and forgot about him. I wish I had stayed single and worked on myself. I wish I could have that time back.