How to deal with all these emotions?

So there is this girl who I got to know around 6 months ago. We had to do a group project. She was in my class since last 2 years but we barely knew each other. So we became good friends during the project. I got to know her a lot. She would share her life problems with me and I would help her out. I would go out of my way to help her. I used to write her huge texts to help her about the situation and she really appreciated it. In fact she changed a lot and took a lot of advice. So according to me we were really good friends. I started liking her during this entire process and became mad over her. I never told her about the feelings. After our break, since the last 2 months we aren't talking much. Whenever we do, I have to do initiate the talk. I have to always be the first one to talk. She also started being really mean with me in general. Giving really late replies and what not. We are doing another project together. This one is going to last for more than a year. I chose her as a partner because I thought we were good friends and it was fun working with her earlier. Anyways she became really mean with me. She would only talk with me when it was related to work. She was quite busy during this time so maybe she didn't have much time. But she would spend time with her other friends and used to really enjoy with them. Since I had feelings, I would feel really shitty most of the time. She never seemed to care about me. I did so much to make her happy and it was like she never cared about me. Anyways I told her 3 times when I thought something would happen to our friendship. I pointed it out to her when she was being really mean. She would always say sorry and that she would try to change. She's still mean with me. She became normal a few days ago but then again back to acting like I don't exist. I hurts a lot because I invested so many emotions in all this. Currently my mind is occupied thinking about it all the time. I can't concentrate on my studies. At the same time she is doing really well with her life. I don't know how to behave with her. Sometimes I feel like I should act mean with her but then I think I will become just like her. I can't act mean with her. I really care about her. I don't know what to do. I don't want to give up on this friendship. It feels like a lot of investment. Also I am trying to move on from my feelings realising there is no future but it's just so hard. Sometimes I feel so irritated that I want no more of her in my life. And If I get a chance to talk to her, I want to spend my entire life with her. My mind keeps changing. I am really confused .

Hey, You’re right not to stoop down to her level and be mean back to her. This friendship is giving you mixed emotiins, which isn’t healthy. So I think this could be a toxic friendship. It sounds like you are the giver - you are genuinely caring and nice towards her and She’s a taker and is mean to you and acts like you don’t exist most of the time, until she has to speak to you. I’m not surprised you're confused, and your mind is conflicting but this isn’t a real friendship and people don’t treat each other like this. I’d start to distance yourself from her.