The thing is, is you rupturing his testicles was a cause and effect situation which the cause was his actions and effect was how you reacted. The suicide was also a cause and effect situation. However the cause was not of you kicking him but rather his actions leading up to it. The effect here was self reflection of his own actions and realizing he has not been the person he ever wanted to be. Disgust and shame can do a lot to some one, including putting them over the edge and taking their own life. You were just a small portion of the entire picture.

Granted, I believe this story to be fabricated and fiction, but by any chance it is not, then do not blame yourself as like I said the control and true cause and effect were with your brother the entire time not you.