The importance of saying Kaddish. The reason a soul comes down here to this world. The relationship between G-d, the soul and the body. What happens when the soul passes on.
A Rav can help you approximate the date of your brother’s passing. Observe his Yahrzeit on that date, and when his soul will be at peace, the tragedy of his death will no longer haunt you.
The Kaddish response is meant to be said with "all the power of your mental focus." Here is a practical guide to saying each word with total mindfulness and focus.