What to do? Please, guys and girls answer this question. I need opinons.?

Ok, I recently started dating this woman. We have mind blowing . There is no doubt that we satisfy each other many times over. Tonight she tells me that she likes to have s and group , and likes to go to the swinger clubs where people can watch. Well, i have had my share of s with women, and I know this is going to sound selfish, but I just don't know if I could join in a with her and another guy. I asked her tonight if I wasn't comfortable with that would she still wnat to do it and seek other options. She stated that as long as we continued to have great then she would not, but am I being unreasonable by even asking her not to do that? I mean i wouldn't have a problem with her and another woman. I don't know, I really dig her, and I want us to stay on the same page, but I just don't know if I could do the group and or other guy thing. What do you girls and guys think?