YANBU to feel this way - but the way you communicate it to your partner could be, if you don't tread carefully.
The fact he didn't give your eldest child the opportunity to buy you a present in the supermarket has me seething. I would combust over this. I have a child from another relationship and it would be a potentially relationship-ending apocalyptic bloodbath. But that's me. And I think that should be treated as a separate issue.
The rest of it... He has tried to do a nice thing, and make an effort. It's misguided and might suggest that he doesn't really know you very well, but it's the kind of thing my Dad would do for my Mum and they are, in every other regard, deliriously happy. He just panics when it comes to buying her presents/arranging surprises, stops seeing her as his wife and goes into 'default gift for women' mode.
Although the fact that there was already a plan in place for your day is an issue, because he knew about this and over-ruled it. So it isn't really a nice thing, it's a 'we're doing what I want to do' thing. Unless you've previously expressed upset that your birthdays aren't that special, you just end up hanging around at home...?
Fuck it. I've tried to be reasonable and give him the benefit of the doubt, because I do believe that when someone tries and goes to some effort, you shouldn't ever throw it back in their face. It is indeed the height of rudeness. But I can't get my head around how he can have been party to all of the planning and then done this. It's not necessarily how it makes YOU feel - it's your kids... Your poor kids.
I'm going to stop rambling. YANBU. I would tell him that you'd love to go out for a meal with him at night, it's lovely of him to spoil you and you really appreciate it, but you'd like your children to have the chance to spoil you too, it's important that they get to do this so they don't grow up to be monsters that only take - WE ARE FUCKING PLAYING PASS THE PARCEL.