How is the husband gtfoing indicative of a mistress or relevant to the question of whether the wife was sane at the time of the murders?

Having people close enough to take you in when your nutso spouse commits triple homicide is not a red flag or a cause to cast doubt on where the guilt lies

I don’t have a mistress but if my wife killed 3 family members, I’m sure I could find someone to give me a place to crash to get away