If you are thinking of ‘doing nothing’, it is certainly an option. Your Gleason score is classed as intermediate on the scale of aggressiveness, and there will be thousands men walking round with exactly the same as you, blissfully unaware they have cancer.
The point is as this stage, it’s probably ‘curable’ - whatever that means, as it often recurs years later, by which time you might have died of something else. If you do nothing, you might live five, ten, fifteen years or more anyway.
I don’t think you ‘need help’ in a psychiatric sense, as to keep calm and carry on is a logical option. Take advice from your specialists, and maybe have another PSA test in three months to see if the PSA number is increasing dramatically.
I had the same score as you, had a prostatectomy, and am now cancer-free. No regrets. But then I am an optimist, not a depressive😉
Best of luck whichever path you choose.