Should I be worried about my boyfriend?

Hi,
A few weeks ago, my bf came up with a these weird questions, like, if the thought of having my legs, or even my tits cut off would possibly turn me on. Not for real, he keeps saying, but as a fantasy.

I found this site in his browser history ( In the unlikely case you happen to read this, I think it's super cute that you used my birthday as your password, but you really should use something more secure <3<3<3 )

Now since you all seem to be into these things. I want to know should I be worried? I really don't want to denounce anyones kink, I get that some weird things can turn someone on, but I'm really horrified about some of the things I saw here. I don't like pain, and the thought of someone would get off while killing someone.... I think that's just sick #(

Then again, I really try to understand my bf, and I got to give him credit, he never did anything without my consent.

I found some, a few images where the artist drew the victim enjoying these things, playing along and I think, if I pretend it wouldn't hurt and it wouldn't be permanent, like in some sort of computer game where you just respawn whole if you get killed. I think at least that fantasy I kinda get. Maybe I could even get myself to like it.

But, here's the thing, I am just not sure, would it stop there? Or is this like a drug where you can't get enough. I'm afraid that if I let my bf endulge these games, he'd eventually want more and hurt me. Or worse, he could hurt someone else, and get in trouble for it.

How difficult is it to "live" these fantasies as a couple? If you get off of hurting someone, how do you and your partner deal with it? Or if your partner does, how do you deal with that? Do you roleplay and pretend? Or do you just tell each other stories what wished or imagined to do or had done to you? Or do you actually let your partner hurt you?

What would you suggest I should do?