Same dude. It's just he is going through his own regrets and guilt. He just got karma and he deserves it. He literally destroyed two lives cause of his own selfishness.
Ikr. I didn't feel any emotions from the letter idk why. Maybe because It angered me thinking how shamelessly he had the audacity to act like that. Moreover his boyfriend again and again begged him and forgave him. Yet he didn't feel sorry at all. The only moment he felt regretful was when he knew about his diagnosis. So why the sudden change of heart? Cause he felt too guilty and he knew how he purposely neglected him.
I didn't cry when I read the letter. I felt disgusted. What's the point of lamenting now when you killed the purest soul who loved you until the end? He is showering his sorrows in the letter mostly cause of his guilt than the demise of his boyfriend.