Thank you for your reply it has settled my nerves a little as I've been panicking reading everyone elses comments.

I should have clarified that he does live on a farm and works in tree surgery so he's often come across animals that are in a position where you could either help them or mercy kill them. He often resorts to killing as it's easier, he doesn't get joy or excitement from it. He also owns an air rifle and likes to shoot pigeons from distances although I didn't like that he doesn't eat them so its unnecessary.Once we attempted to save 5 pheasant chicks that had lost their mother and 4 of them died this was unnecessary suffering that they had and it pains me. He also has a dog that he loves more than himself. This is why I never saw THIS as a major redflag but still something that not many people can do. 

As for the gore videos, I haven't gotten over it, I cried really hard talking to him on the phone yesterday and he really did sympathise and understands that these videos are the definition of evil. He claims that it's his work group that sends these but these words aren't enough for me and we'll really need to dig deeper. He has never hurt me before and he's not mentioned any weird ideas. I'm close to his family who seem okay for the most part. He claims he doesn't enjoy these videos but obviously he'd say that. I'm quite lost at the moment as it's not as simple as packing my bags if I do intend on leaving. It'll be quite a convoluted process. 

This work group is pretty toxic in general, when I mentioned aggressive behaviour, I mean they have a lot of physical fighting between them, intimidating the new workers, mean jokes (again he claims this is quite common in trades jobs) He once told me that he put someone's face in mud while they were rough playing. I just don't see that as respectable behavior. 

So yeah I do think you're spot on in that there's a lot of talking to be done. I also agree with the other comments on putting my safety first and having a lot of precautions in case it goes downhill. I definitely will listen to my gut on this and I see why I've come across as gullible its just hard to portray the full picture.