What should I do in this situation?

I am in clg and always noticed that a girl (S) is always standing alone and almost never interacted with anyone unless it was necessary (like during team projects) .

I realized that she was introverted and does not talk much . Seeing (S) like that I remembered that I was an introvert myself and took me a very long while to break out of my shell and take the initiative to talk with others . And I always thought if someone just came up to me themselves and started to initiate the talk and helped me out a bit then I would have been able to break out of my shell and gain confidence earlier.

So I approached her and talked with her and whenever I saw her I will approach her just make some casual talk as a friend and noticed that she was getting comfortable and was even able to initiate a conversation with other people of the class as well . And I also learned that for some reason she started clg late so she is 4 years older than me

But after almost an year she started to mention that (S) told her mom about me saying that she made a great friend and after that whenever we met and talked she always says that her mother always talks about me and ask questions about me and her little sister does the same as well

Then I noticed her giving me weird glances and thought it might be possible that she got a small crush on me and I always though of her as my friend only and a younger sister so during our next conversation I casual changed the topic and said that I am not interested in dating anyone right now and will only think about love when i am financially stable and nothing happened at that time .

But one day I got a msg on my insta from her little sister asking me if I was dating her sister . I asked her why she thought that and she told me that her elder sister always talked about me when (S)was with her mom and sister and she mentioned that she talked about me for like almost 2,3 hours daily.

Idk what I should do . I never flirted with her and only touched her cheek once to remove something from it (According to my limited understanding she has a crush on me that's what I can tell . But I don't want a relationship)

Open to all suggestions and your views on how to handle this matter . I am not good with emotions so if someone is good with them please tell me what to do