It’s impossible to know if a choice you didn’t make was good or bad. For all you know a choice you regret not taking could have led to great loss and trauma. It’s normal to have these thoughts but not healthy to have them as dwelling on the past causes depression just as dwelling on the future causes anxiety. When you find yourself experiencing these thoughts. Be compassionate towards yourself, ground yourself in something you’re happy about in life right now that you wouldn’t have otherwise.