I actually feel really bad for him, because he isn't inherently evil, but due to being raised by an abusive father that equated violence to love, his entire world view is fucked up.
He latched to the first person that didn't beat him, and it is obvious that he behaves like his dad because that is the only way he really knows how to behave.
Kid is a mess and I feel bad for both of them, I honestly think he really meant every single word he said to her that she latched on to, but he was simply too scared of loosing her that he started seeing everyone other than them as a threat.
I think it would be great if he actually ended up sacrificing himself to give her a real chance at finding happiness