This is a tuff question because safety is usually an illusion. I do know that kids who come from homes with disfunction are more likely to be abused. But your are right that all you can do is talk to you kids and empower them to say no. And if something does happen handle it the best way you know how. My parents couldn't protect me but they did step in the love me through the aftermath and because of that I'm still here and I've been able to grow into an amazing person despite my struggles.
Keep calm and carry on!