Try to blank sheet it as best you can. Done is done, got to move on and if that means erecting barriers and being civil but cool with him (not avoid) if forced to be near him due to sports events then... with time it will get easier.

I think many of us have had issues where we've become needy to others and they eventually couldn't take it... but rather than let it batter you down, brush yourself off and learn from it.

While at University I became quite reliant on a girl who helped me while I was in crisis... there was room for it leading to a relationship... but due to some horrible things that happened back home she could no longer shoulder the responsibility of being there for me and yeah, I understood, I backed off... but it hurt really badly.

She tried to re-establish friendship a year or so later but I had moved on and though I was very polite, I refused... once bitten, twice shy and I didn't want a repeat of that situation.

Not sure if that helps... but sometimes these experiences can make us stronger or at least prepared for future interactions.