Dating in Secret

I’m a lesbian who having an affair with a married woman. She says she loves her husband as a friend but she’s never been really attracted to him. We’ve only been involved a short amount of time and she’s only ever been known as a heterosexual, so she’s not ready to throw everything away for me yet. And that’s fine with me too: I don’t need a serious relationship now either. But I do want to keep seeing her and I want to keep it quiet. I know you don’t approve of deceit, but you have to have some knowledge about dating in secret. What do I do and not do to keep this under wraps until we have a solid plan about what we want?