Xander seemed to be preoccupied, and he was obviously, er, out of it. Actually, he looked like he was fighting back emotions. But, in reality, he was fighting much more.
Xander was shaking as he went outside into the backyard; he felt lik he was losing the battle. No! NO! He ran, and dind't care where he was going. He just ran. Had he been paying attention to whre he was going, he'd realize he was heading for the woods in the back.