I Sacrifice My Happiness for Him

I gave up my happiness so that the man I love could be happy. He was no longer happy with me and only saw me as a friend and no longer as a girlfriend. His love for me changed and he no longer loved me the way I loved him. It hurts me deeply to let him go, but I wanted him to be happy even if its not with me. I'm sadden truly I am but what am I to do? I can't force him to love me or be with me. I guess I'll just life my life and harden my heart. Who knows maybe he will want me back, but that's just hopeful thinking. How can he when his other ex is in the picture still and she's his Best Friend. There is nothing I can do. He needs to see for himself that she's no good.