I think you really do have to stand up for yourself.

When she says things like she should have gotten a Porshe vs. a Mercedes..you should reply with "listen chic, your lucky to drive a luxurious car while my family sells cars to pay rent". Your really complaining about that stuff to me?

And the next boyfriend she meets that she wants to marry I would point out to her that she is very easily wanting to marry every guy she meets...and give her examples.

Stop taking this crap..come back with your replies and maybe she will "cut you" out of her life and that would be a blessing for you.

She tells you how SHE feels. Its time for you to tell her how YOU feel.