Well, it might have been nice if he DID buy you a new bra - but really, that's trivial. A new bra isn't the same thing as breaking something of true value. It's easier to just go to the store and pick one up for twelve bucks. (Besides, whether he broke it or not doesn't matter, bras need to be replaced over time anyway.)
As for your birthday - it's *post* break up so really, there's not obligation whatsoever to treat you anymore, or you, him. Even if you broke up on Sunday and your birthday was Monday, just by being ex means if he decides he doesn't want to acknowledge your birthday he doesn't need to because you've already established that you two have moved past being linked.
I'm not interested, nor do I understand the "friendship after breaking up" thing. I can certainly understand not being enemies, and being cordial if you see each other, but exes are exes for a reason, and your time together means that you're done and it's time to either enjoy being single, or work on finding someone to fill the spot where birthdays will be special with someone else, and broken bras are broken because of some good sex - with someone new. :)