a girl who was intrested in me lost intrest the moment i tried to start something with her...

Here is the deal,

i got to know a girl two weeks prior.

I started studying and she as well (the same subject).
She is very kind, like literally she does not hesitate to talk with strangers and always asks them in a way you would only do in a long term friendship and seeks new contact (always).
So she goes all day around with me, asks me every possible thing.
I had some moments where i thought she took an interest in me, but reminding myself that i did not have a romantic relationship since elementary shool and the fact that she is very kind and an extrovert, i tell myself that's just her way of treating everyone.
That was the first day, next day she asks me out on a coffee, i agree we talk a lot again, laugh a lot, find out that we have many common interests.
The week passes like this, we go eating together my sister was introduced to her, they both like each other. Some other student (nice guy too) joins in on the fun but has really the hots for the girl.
We wander around town, i with the guy a little behind my sister with the girl.
I get later told by my sister that the girl made a remark about that there are good guys in town, looking at me, asked about the topic boyfriend search.
She also once misheard me saying i don't want a relationship and was eager to change that view (of course i said i was only interested in something long lasting and serious).
Party time arrives, she is looking for a place to stay and ask me if she can stay over (at my parents house) i agree.
at the time i did not feel very good so i tell her she should go and have fun with my sister, but she really insists about me going with them and even wants to stay with me if i don't go.
My sister offered already to find out if she is interested in me since she beliefs it, so does my mother (on the basis how she acted around me and the information that i told her -> the girl randomly asks me on whatsapp, how i am and what i am doing right now).
I told her on some occasions that I'm a boring person, she responded that that isn't true and its only my perspective.
I have psychological issues regarding my social life (no friends, just people i know good enough to talk for the time being) since i had some rather sh*tty experiences, i brushed those feelings for her away. I am very introverted. So my sister and mother pushed me over the edge to take action. I meet her with another guy, i know she is not interested in him but my mood just dropped dead. Because how kind she is she talked a lot with him and of course how introverted i am i did not.
Made an excuse and walked away. The following afternoon i write an apology letter and tell her it is hard for me trust people that's why i acted cold (she told me before that i could come and counsel with her, since she guessed something was not right).
Next day i ask her out on a coffee, she agrees to come after class, something comes up and we have to collect something for class, i wait outside and receive a message from her that she already left for the class thing. I go there collect my stuff (it took some time) she left again telling me she is gone eating. Class comes around sitting in the middle row, clearly visible she goes two rows behind me sits down with strangers (like they are all sitting and she joins them), class ends she leaves, not saying hello or bye.

I don't know the moment i start giving into my feelings, start caring, I'm reminded of my own incompetence to get the other ones feelings right...

I tried so many times to stay positive on this matter but right now i want to be alone cry, and be never reminded of this.
F#ck this guy who said it's better to have loved and suffered than to have never loved...

Best regards

NathanMercer