Sorry, but no. You were not lucked. There was no hax involved in that victory. The only turn that could possibly be construed as luck was when Eric's Swampert froze your Zapdos, allowing Blissey to switch in for free. Had that freeze not occured, Swampert would have been KO'd on the following turn, allowing Blissey to switch in for free anyway, leaving the rest of the match to play out exactly the same way. Swampert was not used again for the rest of the game, so its survival was irrelevant. The only difference in the end is that the score would have been 3-0 instead of 4-0. It was a fair match and both sides played well. You made a bad call early on, letting Forretress fall to Infernape so early in the match. I see the logic in your prediction, but it was too early in the match to make such a gamble, and the reward of one more layer of Spikes/Stealth Rock was simply not worth the risk. The fact of the matter is that your team just had a huge MixApe weakness, and Eric was able to exploit it well.
Beyond all that though, why is it wrong to be courteous after a game even if you DID have bad luck? Sure, you can argue that you were going to Roost on that turn and hope that Swampert didn't predict it and use Earthquake instead. Sure, maybe the whole battle could have been turned around and you might have won. But you know what? It shouldn't matter. Regardless of what happened, neither player did anything underhanded and neither player attempted to cheat. A game is a game, whatever the result. Unless you just really can't handle losing, there is no reason to not at least make a display of good sportsmanship and give a simple 'gg'.