The police confirmed that messages of a sexual nature were sent to Jess from a man. There are only two ways this could have happened.
1) it was Chris
2) a hacker/someone pretending to be Chris.
Chris never mentioned that he was hacked. If it was a hacked, you wouldn't go after the victim who received those messages, you wouldn't proclaim that they had mental issues. It was confirmed that she had received those messages. A man was confirmed to be messaging her, yet the Ingham's constantly kept the line that she was at fault/she was lying etc. Now if it had been another man messaging Jess, the Inghams could have explained that had happened and it was being investigated. Even if they didn't know about someone impresentating Chris in the first place, they could have gone back and said "look, this happened and we feel for Jess and it's being investigated." Plus, they could have got the police to investigate further.
But that never happened. Jess never got an apology when it was proven that she had received the messages.
The only reason you'd keep accusing the victim of lying, after it had been proven she'd received these messages, is because the personing who was victimising, is the one that sent the messages.