Well you won in the end lol so why care?
Ofcourse she is upset. Bitter and confused because she knows she should be happy for you!
LOL Ahh the twisted pain of the knife sliding in your back . . .
You didn't just compete for the same job, she told you the job existed. Thats some bitter irony for her.
Honestly though you didn't really do anything "wrong". Its just that personal relationships are more complex that simple matters of right and wrong. Something you obviously know or you wouldn't have posted
The upshot is that you get to continue eating and going to school because of this job. So I would sleep well