There's a reason why it's called a private life. Did they need to know? We're they getting suspicious? I think if you knew this could be the outcome and there was nothing to gain by telling them you probably should have left it unsaid. As someone that is a blabber mouth I often do what you do and tell people who don't need to know.
Now that it's out, just refuse to talk about the subject, tell them it was a mistake to bring it up, and that you don't want to strain your relationship any further. Don't cut off communication. Don't run from your problems. Stand up to them and show them you aren't a child anymore.
"Regret for the things we did can be tempered by time; it is the regret for the things we did not do that is inconsolable." - Sydney Smith
Kyle: 27 year old male
Katie (rymmare): 25 year old female
Kids: girl: 5 years old, boy: 3 years old