Forum:Caius VS, Summon Reactor

I was in a very close duel. Probably the closest I've ever had. It ended up as a tie. On the last turn I had 950 life points and my opponent had 100. I had summon reactor face up on the field. He monster reborns Caius the shadow monarch.Idk if it was a tie or not. Does he lose 800 for summoning BEFORE my Reactor is removed from play, or do I lose 1000 at the same time when he activates Caius' effect? Who won this duel?