Thank you for your thoughts on this - it really helps to know I'm not alone.
It he found out about a camera or device, I have no idea how he would react - he is an animal, and if my son was there with him, that would be too dangerous. As you say, its so hard to prove - only a couple of people have seen the psychopathic side to him. Me and his Mother - although she used to dilute his behaviour when I was married to him, telling me 'men never grow up'. A totally different issue, but hey, you know how good they are at playing the charming man.
I think you are right about his new wife, I am hoping she is 'normal', and plan to get to know her as best I can, when he is out of the country with the Army. He will groom her to relay all information back to him, obviously, so I will have to be careful what I say.
My question about whether the second marriage will be different, was meant around, when she starts to suffer at his hands, or is abandoned, as per his usual pattern, I would like her to know that she can come to me for safety. I didn't have anywhere to go for sanctuary, so I know how terrifying that was.