My group of friends is splitting and I'm torn?

I thank anyone who answers in advanced, this is really complicated and I don't want to make a mistake. I've been friends with a group of people for about 4 years now and they're all really good friends. Lately though, they have been drifting apart into two separate sides and it seems obvious that they will become two groups. I really want to be friends with all of them still, but there's a problem. The first side is a good influence and generally never does anything wrong, but they always judge people and talk about them behind their backs which is something I can overlook I guess, but only because the other side is there to balance it out. They reflect exactly how I was raised. The other side not only has the friends that actually treat me as more of their friend, but also never judge and let people live their lives, something I have always been known to do. This side even includes the girl I like and who everyone says I will end up with eventually. While this side seems much better, they've turned to drugs (not something i judge them for, but my parents are the most judgmental people in the world and if they catch me I'm dead). This side represents more of what my personality is like. If I had the choice, I would go towards the second side, but I was raised so much against it that, I could barely picture myself doing it. Should I man up and just go with it, or stay with the first side ready to blow up in their faces? One last detail, I've been told many times that me and the girl I like are pretty much identical in personality, brains, and especially parents. She has an older brother that can cover for her, but that's something I lack, so I would have trouble keeping this from my parents who are hell bent on the idea that even doing weed once can screw your life up. Please take this with all seriousness.