Assuming it’s real, one thing to remember is that you make the decisions and take the actions you took based on the best information available to you at the time. You only control yourself. Your job and duty was to review code and make professional judgments. You did. You did nothing wrong.
If true, and I hope it is a troll, he chose to take professional disputes and make them personal. He chose to get stressed out by your code to the point that he attributes it to his demise. At the end of the day, his inability to behave like a rational, professional adult was his undoing - and then doubled down by cowardly making it your problem, lashing out, then disappearing to hurt you.
Hold your head high. If reflection inspires you to approach things in a different way, do it to improve yourself and align with your values. Don’t let guilt drive your being.