I'm asking whether or not there's reason to believe that he is mentally ill, not whether or not there's reason to believe that he was an abusive husband. 'Mentally ill' has a specific meaning, not that you'd know it from the way the concept gets thrown around in mass shooting discourse.
By all accounts he was an angry man, who besides the wife beating, used racial and homosexual epitaphs constantly and talked about killing to his coworkers. He killed 50 people and basically committed suicide by cop leaving a 3 yr old behind. Whether that makes him mentally ill or just an angry bigoted narcissist I am not professionally qualified to tell.