往事终究不堪回首
[wăng shì zhōng jiū bù kān huí shŏu]
'Wang Shi Zhong Jiu Bu Kan Hui Shou' means 'Ultimately Regrettable Past Events Not Fit to Look Back On'. It poignantly refers to memories of the past that bring regret or sorrow, acknowledging that revisiting them is painful. Someone might use this as a way to show that they've moved on from their troubles while admitting these memories were difficult ones.