Having been through a bitter divorce, I speak from experience. Don't rise to the bait, unfortunately mums can ignore court orders, not turn up at court claiming to be ill knowing that you will still have to pay your legal costs, not comply with contact orders etc and the judge will normally rule in their favour anyway, she can't prove it, you can't disprove it so theres no point arguing about it! its just not worth it unless you can disprove it or discredit her but don't be tempted with tit for tat as the judge has seen it all