At 14, a person cannot give meaningful informed consent. Legally and morally, this was child rape. I do not see how this would not result in severe penalties for anyone over the age of 18. I recognize that sometimes there's some leniency if the age gap is less -- for example, that an 18 year old with a 14 year old would suffer less penalty than a 28 year old with an 8 year old -- but there is no legal room to factor in whether this was consensual, because it inherently cannot be unless both parties are past the age of majority.

So I'd handle this like I would with anyone I found raping my child. Also, ethically, a boarder sexually approaching one of your children is a completely different breach of contract.

I haven't bothered to read how Joanne handled it. But I would call the police and press charges. How my child handled it would be a separate issue. If the child was a discipline problem and an entitled shit then that's unfortunate but even an asshat child should not be sexually assaulted.