MJ was dead, and there was only one explanation: Harry. And for Harry to go that far, for him to kill someone he loved... it had to be bad. Like back home, when he'd become more Goblin than Harry to the point where he was barely recognizable. History repeating itself, and Peter hated himself for not stopping it. But he could beat himself up later; as much as he hated leaving MJ's body for the Avengers, he didn't have a choice. Gwen was in danger, and so was anyone else Harry came across if he managed to get away. He'd never moved so fast, and when he reached the Estate he launched right over the gates and onto the driveway. Maybe he should've waited for this Jason guy before going in, but he was too keyed up.
Of course he was suited up, since he couldn't fight Harry-Goblin as Peter Parker, but he wasn't expecting to come across what he did right on the front steps of the mansion. A fallen form, blonde hair and torn clothing; he literally felt his heart stop. No, no, no.] Gwen? [He broke into a run.]