I think you’re right.
If she did indeed know he was driving, I think she might be held liable for some very small percentage of blame and damages.
I mean a SMALL percent. Like no more than 10%.
Nah. Texting means you can read it later. Like email.
I disagree. Texting is an asynchronous form of communication, like email. The recipient can read and answer at his convenience and when he is safely able to focus on the message. The sender is not responsible for the timing of the recipient's response.