He's ignoring me. What can I do....?

Me and this guy work together and have the same circle of friends. He was interested in me, but I made it clear I just want to be friends with him. Since then he's cut off all contact with me and we're ignoring each other at work. It caused a huge rift in our group of friends too. The boys are on his side, the girls are on mine. And we don't spend time together as a group anymore. If we are at the same event he will totally ignore me. I've tried talking to him about it, but without success. What can I do? I am sad and hurt, because I miss him as a friend and I just want things to be the way they used to be where we can all hang out as a group again....