I am married to a vanilla man, and we have 2 kids. I do have cybersex online, in chatrooms and such, and it was there that i met my MAster.
When I was younger (i.e. just out of High School) I moved in with a boyfriend who said he was into 'the lifestyle'. It turns out he was just a sadistic bastard; I ended up in the hopsital for a few days after going into shock after one session in which he was drunk and did not respond to our safeword.
The experience frightened me; the thought of how close I came to dying scared me. I stayed away from BDSM for a while, and eventually met my husband at work. We dated for two years, then I got pregnant and we got married. That was three years ago, and I love him dearly; I can't imagine living without him. I would never leave him. However, there is still that 'itch I can't scratch', the need to be dominated and used, and my husband is horrified by the very idea of tying me up and hitting me.
I was in a chatroom when I met a Master who didn't live all that far away from me. We got to talking, and then we met, and we had a few scenes together. My husband did find out, however; he came home from work early and surprised Master leaving our apartment. He didn't say anything about it at the time, but we did sit down and have a talk about it. He said he understood that i had sexual fantasies that he couldn't fulfill, but he also said that he didn't want strange people at our apartment, and that people would talk. He asked me to confine my scening to cyber, and not extend it out to real life. I have since restricted myself to cyber, in accordance with his wishes; it's not as good as r/l scening, but I love Hubby, and i respect his wishes. And I have found that it is better; I don't have to juggle schedules anymore and try to fit Master in with Hubby's schedule and mine. Cyber may not be as satisfying as r/l, but in the end it's better for our marriage.
I'm not trying to say its right or wrong; I'm just trying to explain my experience. I had to find a balance, one that would fulfil me and still respect his wishes.