I would do everything different. Damn why isn't that possible? Fuck
The thing is, we don't grow or improve or gain wisdom without making mistakes or experiencing suffering. That is part of the very nature of life. We do not usually become who we become based on talents or potential, more often it is because of circumstances.
The Stoics worked around this by looking at every challenge and obstacle as opportunity for finding a hidden treasure, such as an untapped ability, an unnoticed resource, or to grow in power, ability, and/or knowledge. If they made a mistake, they acknowledged their imperfection and resolved to learn from the mistake and move forward with the intention of doing better.
I'm not saying to turn your frown upside down. Shit hurts. The Stoics didn't run from their emotions, they acknowledged them and worked with them.
I'm not trying to preach Stoicism to you, or to preach at all. What I'm trying to share is self-acceptance of being human and fallible, but also being human, resilient and full of untapped potential.
Finally, time may not heal all wounds, but distance creates a boundary, and with time, this won't sting so much, and you will develop new feelings and thoughts about the past. Your grief is allowed to have space, but in time it will not be bigger than you, it will take up less space as you move forward from what you regret and become more than the act, more than the regret, and more than the grief.
I say this as a 48-year-old woman who has suffered, mourned, and grown. My reasons for contemplating ctb are thoroughly external, not because I seek to destroy myself for things I cannot undo. I do not speak down to you, I recognize and honor your right to self-determination. I cannot and do not promise good outcomes for you, but I hear your suffering, and I see in it and in you the potential for good outcomes. I speak with deep respect for your pain and fellow humanity. I send you a compassionate and caring hug.