I've always been mildly depressed/traumatized, but my tipping point was definitely dating someone and falling in love in my first year of university. It was my first serious relationship, and when I got dumped I didn't know how to manage the emotions and I attempted suicide a few times.
Honestly, I wish I had stuck to flings, or even dated earlier in high school (get the trauma over with young), but I was so antisocial.
And then I took a year off of university, and by the time I went back, everyone was a year younger than me, and even if they weren't judging me, it felt like they were. So that made me skip classes to smoke weed instead, all on my parents dime unbeknownst to them.
Now I'm working a stable job and my life would probably be tolerable/acceptable for anyone else, but because of my abusive parents all my mind is willing to accept is that I'm a failure and I could be living a completely different life now, and that it's too late for me to do what I want/be where I want to be in life. That "what if" is just stuck with me forever. The potential I had that I threw away. And I live every day thinking to myself how pathetic I am. It's just not worth living life like this.