Advice Column Tackles BDSM

I thought this advice columnist about explaining your BDSM activities to nosy or concerned friends and family gave the girl in question some wonderful advice. If you're interested to read the rest of the advice column, click here. Scroll down to Washington, D.C. to see the one about BDSM, but there are several others on the page. The advice about BDSM I've also copied and pasted here:

Washington, D.C.: My live-in boyfriend and I have been together for three years,
and our sexual activity tends to be a bit ... unorthodox. Both of us are into
BDSM, which (on occasion) leaves bruises and marks on whoever is "subbing" that
night. These activities are mutually fulfilling, completely consensual, and
always done safely and sanely (safewords, aftercare, etc.). Unfortunately, a
friend of mine with whom I work out has noticed a number of bruises and the
occasional mark when I've changed in front of her. Of course, now she thinks I'm
stuck in an abusive relationship. For the last few weeks, she's been referring
me to literature on abuse, calling me at odd hours to make sure I'm OK, etc.
Whenever I start to insist that, no, this isn't what she thinks, she assumes
that I'm just being defensive and validating her concerns. I don't feel
comfortable giving the details of my sex life to her or explaining that if she
were to see my boyfriend, he would look much the same. But I also don't want my
friend to think that my loving, understanding, admittedly kinky boyfriend is
harming me, and that I need help out of the relationship. How can I defuse my
friend's concern while still keeping my private life, well, private?

Emily Yoffe: You don't need to give her the details, but short of
telling her, "If you don't stop, I'm going to be tempted to flog you with a
whip—because that's what 'Sam' and I do for fun," you have to get a little more
explicit to get her off your back. Next time she brings it up say, "I understand
your concerns, and I know you think I'm covering something up, but Sam and I
engage in unorthodox, mutually satisfying activities that aren't for everyone,
but are for us. Please accept that I am completely in control of my personal
life, and I appreciate your caring, but this subject is closed."