Oh there was lots of things he could have done: See a psy, retire early on to get treatment, isolate himself, try to fin a cure ect...
Murdering his family was the last thing to do; anyone who supports Benoit is just supporting a murderer and that's wrong.
Having an excuse or justification doesn't make him less guilty. For example, Bin laden probably also had some kind of beliefs and reasons behind his atrocities but at the end, his acts was heinous, is heinous and will remain so ever and ever after.
Personally, if someday WWE inducts that guy in the Hall of Fame (which will never happen but still...), I'll stop watching it.