First of all I just want to say that please leave that person immediately. I can say your feeling as true love. But that person does not deserve you and your feelings. He uses you as per his convenience. Initially no girl in his live so he gave you importance. Once he got another girl he forget you immediately.
When that girl kicked him and he become lonely then he again come back to you. Now again other points start coming in his mind. your health related.
I just want to ask one thing. Do you have any self respect or not? You are also a creation of almighty God. Every creation of GOD is beautiful. So stop thinking negative about yourself and your hole in your heart. Now a days medical science is so mature that you can live happy and long life.
A person who changes his view as per the circumstances then how you can believe that person. So stop thinking about that looser(As he is going to loose you). This world is full of good people so move further.
Personally I have also go through with this situation. Initially I felt bad that a person rejected me. But as time passes I start feeling that all the things which happened in my past are good for me.
So please leave that person immediately, forget thinking about that person. Remember that you are not a begger on whom he can show his pity.