Oh Purple that's horrible. Vent, grit your teeth and call him horrible MN names in your head. I always refer to my ex now, to myself, as twat. I find it helps to minimise him, and makes me laugh as it's so childish!!
Just think how nasty it must be to have to spend your money on "stuff" so that your children will think better of you. D'you think he had a really awkward chat with his family, about how they often forget birthdays etc but how he needs them to ramp up the gifts to make him/them look good? What a bunch they must be, that's got to chip away at your soul a bit, eh?
In 6 months time your kids won't remember the shiny stuff gathering dust in their bedroom. They'll remember that you were there, on Sunday night, with a home cooked meal.
Weirdly my ex is the opposite with stuff. He considers his maintenance to be on a par with a holy sacrifice! He does take them out, buys the odd thing, goes on holiday etc. But he never, ever, buys anything practical, such as school shoes, a practical item of clothing etc.
I recently purchased everything when my dd changed schools. He didn't contribute so much as a pencil. This is his way of saying I work so hard, do my bit, the rest is up to you, not my concern (so kind of Disney Dad but slightly twisted). What he doesn't realise is that my kids will look back and wonder how on earth did mum provide all the basics, because I think that's what they remember.
For all the presents and meals, if they have a bad day tomorrow at school it's you they'll want to run to. It'll be your voice they want to hear, your arms to give them a hug. Kids are smart.