Difficult to deal with what i feel. It!

I feel very sad, i want to talk to a person all the time and his actions affect me a lot, i feel deprssed most of the times and it feels like there is nothing else beyond him, when i try not talking to him i fail terribly. I feel there is nothing beyond him. I feel at the top of the world when i talk to him and when i dont get to talk to him i feel depresses. It is affecting my sleep, my well being, i feel mentally tortured by ny emotions. I had a break up from my past relation of 4 yrs, 2 months back, he was the person who helped me in dealing with it, and i fell in love with him and he is not. He was okay talking to me but i get hell emotional, i feel this strange pain in my heart when i dont get to talk to him. I really need help, u dont know how should i deal with it