My T once suggested, when I was having trouble expressing anger, that we could go outside and I could throw ice at the wall of the building. I declined...too self-conscious, with her building being a big office building. However, when I got home, I took a big cup of ice, went outside and started hurling ice at the wall of my house. It did actually help.

Maybe that's something you could do before session, to kinda get some of the anger out.