Your words: "So I confessed my feelings to someone, we've been friends for more than half a year now, and I decided to tell her. She said no, and that she wasn't ready for a relationship, and I was expecting her to delete all connection she with me but she said she still wanted us to be friends."
My response: Do you think it's even possible for you to be "just friends" with this girl knowing that she may never want anything more? If it's too painful for you to ever consider being her friend, why not stop being with her and focus upon getting a new girl to focus upon. I know it's a tough thing to consider, since rejection is never easy to take, but instead of making yourself miserable chasing the thoughts of having a girl who isn't interested is counterproductive to your emotional health and social life.
Your words: "I still tried a little bit, she tried to change the topic, I directly asked her and then she said stuff about "losing hope in love and having no emotions anymore" I still tried..."
My response: She may have been feeling pressure from you that she wasn't ready to accept. From what you're telling us here, she isn't in a state of mind to get into a relationship. Sometimes people initially feel that way and then change their mind. I wasn't in a state of mind to date the guy I'm with now because I had recently been broken up with a guy. I gave it a couple of months of time for reflection and healing, and then we started seeing each other. Strangely enough, the guy I kept backing away from when I was in college is now married to me.
Your words: "But I still can't get it out of my head, I really want to be with her but there's no way for me to try any more, I know I need to respect her decision but I can't control my emotions."
My response: I know you really care about her, but why not stop seeing her for awhile. Maybe she'll change her mind. Maybe she won't. I don't think you should hang around waiting for her to be ready for a relationship with you, because she may never be ready.
Your words: "Wtf am I supposed to do now? I'm a nervous wreck, I've never been this way."
My response: What should you do now? You should either accept that she only wants to be friends and date others or wait for her to be ready. I think it's more certain that you will find another girl who will interest you. In the meantime, try to get reminders of her out of your life and stop seeing her altogether. Good luck!