This is entirely a personal take but I find the indirect way JD structures his sentences to be unnerving.
I've been in a relationship with a man who was very manipulative – he lied, twisted the truth, avoided, denied, deflected and blamed as a regular matter of course. So I've gotten fairly good at recognising speech that's deliberately vague, avoids making outright threats in favour of oblique ones that have plausible deniability, and focuses on the 'better future' so as not to address the problematic past or present.
'The next move, if I don't walk away, it's just going to be a bloodbath. Like it was on the island, it's not worth it. Why be miserable, can we just have some understanding?'
Who's going to cause the bloodbath?
'Just thought you should know there exists a book titled Disco Bloodbath, that's all.'
Why does he 'just think she should know'?
'I made a huge mistake. I won't do it again.'
This is a classic mantra for an abuser, of course they always do it again.
'She will hit the wall hard!!!!'
'I can only hope that karma kicks in and takes the gift of breath from her.'
Wistful expressions of harm to his wife that are deliberately vague about how she is going to come to be harmed.
I used to really like JD but the way he's presented through the whole court case feels really sinister. As someone mentioned upthread, his whole performance of trying to come across as funny and quirky and long-suffering through the questioning in the case that he brought himself really gives me the heebie-jeebies. I can see Amber's no saint but I think she is almost certainly the true victim here.