If you make the best decision with the information you have at hand you shouldn't regret the decision you make. Retroactively the decision can turn out to be a mistake, but those mistakes you can easily accept: at the time you believed you made the right decision.
There's no need to second guess yourself, beat yourself up and ask "What if?". You can make a decision and if it turns out to be a mistake, just say "whoops" and move on.
If you regret nothing you have done at the end of your life it probably means you never made any serious, life-ruining decisions or you were incredibly lucky. That in itself is something to contemplate long and hard (luck or tragedy). Significant risks come with significant ramifications and sometimes taking a risk doesn't work out. Perhaps the question if you never took such risks is would your life be any different if you had taken the riskier path.
You don't walk away from accidentally killing someone or destroying their life with just a "whoops" unless you have something seriously wrong with you.