what???
If Kaine was trying to put pressure on TH, what better way to get public opinion totally against her than to make it look as if she were sexting someone that she hardly knew?
MC IS Kaine's old friend, and it's hard to say how much contact they've had recently. Kaine COULD have sent MC to the house to keep an eye on her. Given where he works, it's also possible that Kaine might have the skills (or know someone who does) to hack TH's phone.
I'm sorry, but the whole idea of TH sexting MC never has made sense to me as it was presented - if it had been someone she went to school with, a friend of hers - even the husband of one of her friends, I would buy it - but I just can't picture her getting involved that quickly with one of his friends.