To play devil's advocate for just a wee bit (and I realize this is an old thread), if you were making 63k while working part time, you *did* make a fantastic amount of money compared to the typical (median) individual salary, which was closer to 28k. Even when you only factored in full time individuals (and as you noted, you weren't full time), you were much still higher than their median of around 51k. If you went about saying you couldn't afford things to people who made significantly less than you do (which was apparently the majority of individuals in the country), it made sense, parental and boundary issues aside, that you'd have been met with pushback and resentment. You *could* afford lots of things; you just didn't want to spend the money on them. But that didn't absolve you of the fact that you did have more money at your disposition than they did.
That said, I fully agree that you needed to change how you approached these folks and simply be more assertive, which it sounds like you did. It's just worth noting that being frugal on a higher income doesn't negate the fact that you have a higher income. This comes up time and again on the forums when folks go about saying they make 100k but spend 50k so they're really middle class.