ilovelamp82 I agree. I have said that I totally understand the OP's feelings but she did ask "or am I being churlish".
So far I haven't given my personal experience because it didn't enhance the debate, but in light of your recent comment I imagine that she will pack the kids summer clothes because in general mothers do what is right and in the best interest of the dc now I will.
My DH left his 1st wife because of her infidelity with NDN and others. He forgave twice but couldn't manage the 3rd time. As she was the SAHM she got custody (as it was called in those days). My DH got access every Sunday afternoon but even that was sometimes eroded on the door-step when he went to collect. My DH paid more than the basic maintenance, bought the school shoes each term for 3 DCs and paid 50% of school outings.
We were asked to have DSD for a weekend. Nothing could have made my DH happier. But when DSD arrived in our home (DH had collected her from 50 miles away) she burst into tears. She eventually told DH that she had nothing to wear other than the school uniform she was wearing: her DM had said "Let your Dad buy you some new clothes".
We genuinely didn't have a spare penny, but I had fabric .... so I sat up all night making skirts, shorts and little tops on my sewing machine. (I remember that she really loved a little denim ra-ra skirt that I made for her that night.)
DC3 spent more and more time with us during holidays whilst the DM 'studied'. DSD had her own bedroom and her own clothes in her wardrobe because her DM would NOT allow her 'home' clothes to be sent with her.
But then the DM instructed my DSD to 'pack up as many clothes as you can and bring them back'. That was a tearful exit because DSD knew she was being 'sneaky' and was trying to hide the extra carrier bags (she was 12 yrs old and trying to please a DM without upsetting a DF). I said that she hadn't got to sneak clothes out - they were hers. Together we emptied all her drawers and wardrobe and sent them with love.
My DH took on an extra private tuition per week to raise the money to replace her clothes at our home.
I know that you said "because in general mothers do what is right" - but I still suggest that the OP puts her DCs at the centre of her decision rather than churlishness, principles or warring. I had to put a child who wasn't even mine at the centre of my decision-making. Surely a Mum can do the same.