I've had a couple sessions like that and I think all you can do is keep talking about it until you don't need to talk about it any more. Sometimes, it may not ever be resolved, but you'll reach a point where you can accept that the session was a train wreck and move on.

As far as grounding - with my T, it's definitely for me and not her. I tend to dissociate very easily and it's impossible to do the work if I'm not even mentally present in the room. For me and my T, grounding exercises help me to be present so that I can talk about the hard stuff and participate in the session. There have been times where I got so lost in my head or lost in memories that the room just completely faded away...not very conducive to working with the T.