Hi Sue! It's fine that you ask more questions. You should ask until you feel comfortable enough to try the empty chair technique. And keep in mind, you do not have to do this if you feel you don't want to. The idea behind it is to let you get in touch with feelings that are already inside but have not been accessed or expressed. In the end, the technique can help you but if you feel you want to try this another time, that is ok too.
How long should I talk for? (or be expected to talk for?)
As long as you want to (stop at any time) or until you feel you have reached the point you have no more to express.
Where do I start?
Wherever you want to. You can start with something neutral or get right into your feelings. What would you say if he was actually sitting there? That might be a good place to start.
Do I talk to him about the impact he had on me as a child, or me as an adult?
You can do either, or both. It's more helpful to do both. He assaulted you as a child so you may want to address that at some point, letting him know how you felt and what you may have wanted to say to him then when you were not allowed to express yourself. Then you can let him know how it has affected you as an adult and as a child.
What sort of things should (or shouldn't) I say?
There is nothing off limits. This is about accessing your deepest feelings about what happened to you. Whatever you feel is acceptable.
Does it matter if I keep stopping?
No, it doesn't. You do what you need to do to express what you feel and feel safe while you do it. You can even ask that this be done in multiple sessions if that makes it easier.
Can I counteract his replies whilst I am talking? (eg Can I say 'I know you will say it was all my fault, but ........... ?)
Yes, absolutely. You can be as confrontive as you want to. And addressing the defenses he used to justify his actions is a great way to get out your feelings.
Will the therapist talk during this process?
The therapist is there to guide you and help you go in the right direction. Your therapist can also comfort you and encourage you as you work through the exercises.
What sort of guidance will she give me, if any?
It depends on what comes up for you and how the session goes. She knows the technique so she will be sure you stay on the right path and she'll want to encourage you but other than that, this is your time to work on how you feel.
Biggest question/issue ...... I consider that the place I see my therapist in to be a very safe place. I am scared that once I 'allow' my brother to be in that room (albeit just in my head) that it will then feel contaminated somehow. I am scared to let him in, just in case I can't get him out of there again!!
You will get him out again. You are letting him in only to help you. Once the exercise is over, the only thing left is how you feel. He is no longer represented because you stopped communicating with him and because he is no longer needed. Plus the exercise may help you feel less frightened by his presence.
Is that as stupid as it sounds to me? I haven't felt this scared since I last saw my brother!
This is not stupid at all. It is incredibly brave. You are facing a horrible trauma and are willing to work through your feelings. That takes strength and resilience. Not many people can do what you are doing.