So, she has to cut her own grass, now? I imagine there's lots of things she is getting to enjoy like that now. Thank goodness I don't have to cut grass here.
Maybe when she starts to vent at you, saying it's all your fault, etc., tell her "I am sorry you feel that way". That way you can disagree without saying so. And if you sense om is putting pressure on her, don't you put any pressure on her. She will realize who's the better man.
Is your S out sick? Or is it a school holiday? If he's sick, I hope he feels better soon.