"I know what I felt!" he frowns at Castiel. He's a volatile person with his emotions sometimes and to be fair, Castiel's probably right. Jack can project his feelings a lot and he's made mistakes before. He doesn't regulate himself well and it leads to trouble. It feels bad to be blamed though, especially as he has gotten better since returning from the Empty. More grounded, focused.

"I don't think it liked what I was. Maybe I seemed like a threat." After a pause, he gets a guilty look. "I guess ... I was, wasn't I?" Since Jack attacked when he felt threatened by whatever was in there, rather than just found a way to leave and do that. If he had blasted his way out to leave, that would have only caused momentary distress. Instead he woke up whatever was there.