Hello Andrea and welcome from me too, wife to another of our PCa men.
Some of our men can only cope (certainly initially) by not thinking about it all too much. Worry about it when it (treatment) happens, but as the others have said it's best to be prepared and to know the possible side effects etc.
If he has already made up his mind (or had it made up for him by the advice of the consultant) then there is little that you or anyone else on here can say that would make him change it.
All you can do is be there for him. If you ask for the toolkit get the hard copies sent to you and leave them where they can be seen. It's possible that even though he doesn't want to discuss it all he may perhaps pick up the Toolkit and flick through it when you aren't there.
The toolkit itself is really useful in giving you, not only information, but also the basis of questions to ask next time he(and you) go to see the consultant.
You know where we are now so if it all gets a bit too much come and have a chat (or a rant - some of us do that and feel better for it !!)
Best Wishes
Sandra