The Kitten Clause

So, recently me and my roommate discussed getting a cat because i wanted one and so did she. Well, i had almost found one when it had already been adopted by another family, so i went to my local pet store to look for another cat that was supposed to be there and i took my roommate with. Even though she first disliked the idea of paying money to adopt a cat she fell in love with a cat. (all the power to her.) and so we ended up leaving there with a cat she adopted. Thats all fine and dandy, but i still want my own cat that no one can take away from me whenever they feel like it.
So i started considering the cat i had been going to look at the day we found her cat. But since we already have her cat i can apparently no longer even consider this one because it conflicts with her cats personality.(what the hell?!).
I dont have many friends here and she is one of the 2 that i have, so i cautiously step on pins and needles to avoid upsetting her, but she frequently slam her foot down on top of my confidence every chance she gets. i am so worried to lose her as a friend i seriously thought about giving up on what i want just to make sure her precious cat (that we have only had a week) doesnt have to share.
It annoys me to no end when she makes it seem like a mightier than thou attitude is necessary. i dont see why my own wishes and plans have to be put on hold to accomplish hers. anyway. this is her cat: 

And here is the cat that I want to adopt: 

Contrary to roommates wishes I am going to go meet this cat. Can't wait :)