[PilotMan]

His escalation when he's in that situation is his response to his feeling of a lack of control about the whole thing. Part of it is 'look I can't stop' to show you that he's trying, and the other part is his genuine alarm that he can't seem to find the 'right' solution to keep from doing it and he's panicking and doesn't seem to be able to deescalate.

He's definitely in his own head. Does he struggle with deescalation in other situations in his life? Are there other situations where he does seem to be able to get control and overcome that stress and panic? If there is, I'd try and recreate what he is able to do in those situations, and try to get him to apply those to this one. It's a place to start. If it seems like things aren't going anywhere, removal from the environment, such as a room, or outside, just away from that one, and take the time to talk and listen can be helpful. It's not a fast process and it takes a lot of patience. Sometimes your sessions will be cut, and if he's got a problem with that, tell him that BP isn't as important as he is, and that once HE is squared away and ready, then you can go back and hit some more.

I think it sounds like you're doing the right thing here. The therapist will have other helpful ideas and plans too, of course. There's no 'quick fix' here.