As of now seems most plausible that his wife discovered something horrific that had her so preoccupied and distracted she didn’t consciously see the oncoming truck. Now we know Joe was cheating on her, but while infidelity , especially then, would be a horrible discovery, it wouldn’t exactly shock a woman that her plagiarizing, liar politician husband was a liar. What would shock a woman is realizing her husband was a sex deviant with their children. Cause then your mind is reeling with so many emotions and worries.

Very few mothers would decide to gamble on suicide with kids involved. Driving in front of a truck is just too likely to be ineffective or leave people in wheelchairs leaving it even harder for them to escape Joe.

As for thinking it was a hit, the driver really seemed to be a normal decent guy who actually got slandered by Joe multiple times.