It could be (not likely but possible :-) that she remembers how she didn't like you (for whatever reason) and things she did to you then, etc. and is embarrassed because here you are being nice and she doesn't know how to respond. I contacted my first cousin on fb a couple months ago and we exchanged an email and then he quit answering ones I sent and nothing happened but suddenly, a couple days ago I got a nice letter in snail mail with copies of pictures, etc. Maybe she's at a loss as to how to respond and is thinking she is not deserving of your friendship now :-)

I think not going to the shower, though more comfortable for you, enforces your feeling that you are inferior to her (your cause for jealousy). It's hard for you to reach out to her but you did and now you're feeling like your hand has been slapped and probably, inside, feel maybe you were "wrong" in some way, that nothing has changed but you have! You are every bit "as good" as she is and were invited to this party and there are other people there; you could make more friends, meet someone new/interesting, etc. Money and looks, we know don't matter that much! What kind of woman do you want to be for you? You have not gotten a negative reply; just a rude silence. That's about her and what kind of woman SHE is.