Rereading it 2nd time by miscalculation, still thinking the same thing(likely) - the ending and the plot-line could've been done in a much better way. There are meaningless, incomprehensible drama maneuvers that prevented the story from being a masterpiece(highly likely).
P.S. feeling guilty sucks, so I personally do tend to think 'what's done - done', me did my maximum, no self-reproach whatsoever, period.