While I understand you have a professional helping you.. I really recommend the book 'Feeling Good' by Dr. Burns. The exercises in it, and the explanation of false labeling we do that causes us problems, are very helpful IMO. I once ruminated over a 4 year relationship, tons of details about it, probably for a year straight. I did one of the exercises ('... and if that were true, it would mean that....?' over and over to any response you have) til I got to the bottom of every negative thought I had about her, me, or the relationship. I am not joking when I say I woke up the next day and couldnt even REMEMBER 75% of the negative emotions I wrote down for the exercises. I was genuinely cured of 1 years worth of rumination in 2 hours of writing things down the way the book tells you to.