2nd option in love ? i need suggestions?

I am being just friends with a guy right now. I am a single parent and he is single with no kids or commitments, We were getting close but none of us really spoke openly about love & relationship with each other. I got to know by chance a few days back that he is back with his ex girl friend again . He said that he is very confused etc etc. To me it's fine , if he was happy or in love with me he would have not gone to the his ex in the 1st place so I decided to move on as whatever was there b/w us was in infancy stage only. But he is now following me frantically , I even ignored a few of his text messages but he somehow manages to get in touch. He is trying so hard to maintain the friendship that even if I want to ignore him in the end I am compelled to talk to him. It's simple that he does not want to let go of me also and his ex/current gf also. What can i do ? I dont want to get hurt and I dont want to be a 2nd choice also ?