Help! Why I am getting so attached to her? How to stop it?

( English is not my first language. Sorry for mistakes.)

First let me tell you something about myself. I am 21 years old man. I had a horrible childhood. I am an orphan. I was taken into boy's orphanage. Life there was challenging. No one loves you, comforts you and guides you. My orphanage was a Christian Institution. We daily had our prayers. The attenders there shout on us and sometimes beat us, if boys became too noisy. There is discipline but you can't expect love, affection from them just like a family. And I also ultimately accepted this lifestyle.

In my opinion these emotions - love, attachments are temporary in nature. I expect nothing. Life doesn't work as we ever expect. These emotions make you weak. You feel depended on others. There are times where I expected if my mom was alive and take care for me. But it doesn't happen.

Now I am in engineering college financially supported by orphanage and school. There I met a girl named Aisha, known her from 1st year.
She thinks I am very serious, frank and rude. She is sweet and down to earth. She is cute.She lives with her father and younger brother. She talks lot about them. I have even met her family. When ever she asks about my family.I lie to her. She doesn't know I am an orphan. I just avoid the question, trying to change the topic. No one knows about my personal life. We became good friends. I know a lot about her. She's an open book. We fight a lot and she knows about my tastes and dislikes.

But things started changing I can't act normal when she is around.
My problem is I don't want to get attached to her. I never felt like this before it is new to me.I can feel I am getting distracted and getting depended on her. I want to be single, free, independent and strong. I don't need anyone's support. I am scared even her presence or absence is affecting me so much. You know like when she is around me I don't want her to be here. And when she is absent I do feel like seeing her face. I don't understand why. I decided to ignore her. I am now ignoring her but now she is spending time with another boy in my class. I am furious. Why the hell she is ignoring me? I know very well once college is over. We won't no longer be in touch. She won't even be interested to see my face.