Your information for their debt and income is outdated. And who cares how much SHE spent on her business? How about the amount HE spent on his affair partners? He accompanied her on most of her business trips so I don't understand why people comment on how she spent so much time away from her kids. He was with her most of the time, why ignore that? For that matter, he was away from them for 5 weeks;SW was never away for more than just a few days. He cheated on her with multiple people; she provided him with a clean home, beautiful children, fun work trips, and enough pre-prepared meals to feed him for 5 weeks while she was away.
I am not real sure what the price of their home vs the price of homes in your area has to do with motive, either.
Many families go through financial struggles and stressors. That's life. They don't all wind up dead. However he reacted to such things is on him, not her. She may have been dominant, which is not a bad thing, but she did NOT control his thoughts and actions.
SW is not responsible for her husband's actions.
Personal responsibility for her and her children's deaths does not lie on her shoulders. He was an adult man with freewill. Whatever problems he may have had with her (IF there were any at all) is one thing, but he didn't stop with killing her-he literally murdered his own children. Toddlers. And not in a quick, humane way, either.
Perhaps he had a personality disorder. Maybe he had a mental illness. Or maybe he was just a jerk with rage. None of that was SW's fault.
He had other options. He chose not to accept them.