I baulk at this over-use of the word "tragedy" as IMO this was not a fatal mistake, believing as I do, that he knowingly shot a trapped and defenceless RS with 4 BTs.
Nonetheless in a general sense, yes it has been catastrophic for ALL families involved, but cannot exceed the loss of the Steenkamps who are entirely blameless.
What could the Pistorius family have done differently, from that very morning?
Do you think Carl should have taken crime scene evidence and don't you think the family ought to have made him stop or at least confess to what he had removed from the stolen phone?
We have an initial catastrophe, if you like, (but really it's a murderous bad decision by OP) compounded by a series of bad decisions .....with all the family steadfastly united behind him .......this is certainly no laughing matter.
BIB, OP's pain will be equal to the Steenkamps, they'll all have to live with it for the rest of their lives.
The reality though is that with the Steenkamp's age and health, they may not be on earth for much longer but OP will have to endure this for maybe another 50 years or so. That is sad. No one wins.