Today my girlfriend who I'm in an LDR with (I'm in another country for work) admitted she had a weird fetish. Upon asking about it she said she liked to think of me and her as the people in porn she watched. No big deal there, they're actors or anonymous couples. She then continued to explain she also likes to visit sites like Omegle or ChatRoulette and pretend to be other people and talk to other people. Word for word she said "it gets me horny, idk". She explained that it's basically like porn, she's just using it to get off and since she's just having sexual talks with strangers and pretending to be someone else it's not bad. She also explained it's only at times I'm unavailable and that she "thinks of me when she's talking to them". I told her no, she shouldn't continue to do that, and that the difference is that she is interacting with another person, and whether she's pretending to be a different person or not she's still sexting someone else to get off. 

My issue is that if she needs someone to sext or whatever she can just wait for me to get home from work and message or call me, and I explained this and how it amounts to emotional cheating, but she seemed kind of dejected by the whole thing. I also explained that I'm not super hurt or mad over it because I can see how she came to the conclusion that it's okay, but it's too weird and seems to easily escalatable for me to be comfortable with.

So my question is, am I the asshole for not approving of my GF's weird fetish when it's online, distanced from her actual self, and is with people she is incredibly unlikely to meet, with no video or other real info exchange. 