...I'm not the sort to be oversentimental about things like this; I won't tell you to do anything like living your life in a way that he would approve of in order to keep his memory alive, simply because if he's anything like me, I'm well aware that that's horrible advice.

Whether he should or shouldn't have died is an entirely moot point; the fact is that he has. The circumstances don't matter as much as your reaction to those circumstances. If you must do something to vindicate yourself, keep living. Doing otherwise is just ensuring that he died for nothing, which is a hideous insult.