All of our current friends know about our activities and have no problem with it (or just choose to not to let us know that it bothers them).
We have friends that we had before entering the lifestyle that we won't tell, but we only talk to them twice a year. We don't tell them because we know that they would be offended, which is why they really aren't friends anymore, they are aquaintances. People evolve throughout their lifetime, and do truly 'grow apart'. One of the "prerequisites" to being our friend is that you have an open mind. Those who don't are relegated to aquaintance status
I guess our opinion is that if you can't tell your friend everything about your life without fear of losing them, what kind of friend are they?