Do you have something already planned for Tuesday? It would be nice to cancel on W to show your boundaries, but the sucky part is for your kids. IMO, unless you have some other plans already in motion for that night the only one that loses is your girls.
If you don't have some other plans I would actually take them. If you have plans then you have plans.
Me: 46 FWS: 36 Married and Divorced 4/07, Pregnant 7/07,False R 7/07 Baby Girl born 3/08 Kicked him out because OW: 7/08 5/10 He realized what he had and lost. Moved home! REMARRIED 3/14/11!!