I Have A 6 Year Old Son And My Boyfriend

I have a 6 year old son and my boyfriend has a 4 year old daughter, we just recently found out they exposed themselves to each other. I spoke with my son about it and he also spoke with his daughter about it. We know now to keep a better eye on them but we haven't brought it back up since we discussed it with them. His ex wife on the other hand keeps prying into her daughters head about it and continues to ask questions and brings it up and is now saying shes afraid to be around my son and scared to go to her dads, he picked her up from daycare today and she was far from scared to go to his house and the first thing she wanted was to pick my son up so they could play. Are we wrong for not continuing to talk about it or is his exwife doing more damage to her