Please don't bring this up to this poor woman. I don't even know how it would be remotely possible to bring up her child or masturbation in a professional setting.
I would keep your interactions with her professional. The fact that you already know so much about her personal life could feel very intrusive to her. It's her kid. It's her apparent discomfort. If she wants to bring it up, that's her choice. The kindest thing you can do is to leave her alone about it, and by your actions, make it very evident that you aren't the type of person who is going to gossip about her or tell others in the office about her personal life, you know? That's what I'd be worried about if I were in her shoes - less that it's awkward with you, and more what you could be saying to other coworkers about her.
It's evident from your post that you don't judge this family, and that you understand what happened is natural, but not everyone would view it that way (case in point: there were immediate, and reasonable, questions on this thread about abuse - she might worry you think the same thing), but she doesn't know you well enough to have confidence that you aren't the judging or the gossiping type.
Bringing it up is just going to make things more awkward, and make you look unprofessional, IMO. Keep work about work, and let your professionalism and actions speak for themselves and I think the awkwardness will go away as she sees by actions that you are someone who won't make her life uncomfortable.