Boyfriend's sexual fetishes

Just out of interest, I took a test to see what you're into sexually, I only scored highly for submissive and vanilla sex. My SO took the test and scored very highly on everything except those two (there were some pretty weird fetishes in there..) One that particularly bothered me was not being monogamous.
I don't mind being a bit rough in bed but the thought of some of the things he's in to terrifies me. I even get anxiety attacks at the thought of porn, and I know he watches it regularly (God knows what type!) He told me not to worry and that he would never force me into anything. 
I don't know what I should do as the whole situation makes me feel sick and like I'll never be able to give him what he wants. 
Am I over thinking this? Or should I consider leaving him? (yes, it terrifies me that much)