Yes, some kind of proactive action seems to be needed to break up the tidal wave into smaller chunks. Perhaps some type of journaling would help, such as deciding what the worst possible thing is that could happen, and then working out a plan for what you'd do about that. It's likely that the worst won't happen, but having a plan for dealing with it gives you a sort of "safety zone."
Then consider the second-worst thing that might happen, and how you would plan to deal with that. So on and so forth.
Sometimes it helps to just start journaling randomly, even if what you're writing doesn't seem to make much sense or be very relevant. After writing for awhile, you might unexpectedly find yourself talking about the scary stuff, giving it shape and form so you can deal with it directly. Or, like you were kind of saying, something you write one day might be a revelation of sorts when you re-read it the next day.
We have a Life stories and blogs board
that you can use for that very purpose if you want. The blogs are kind of "sacred ground," so you shouldn't have to worry about criticism from other members. It's mostly just a safe place where you can talk about your life, feelings, struggles with poly, etc.
You may find it helpful to read some of the other members' blogs as well. Sometimes you'll be surprised at how much you can relate to the other people, and realize that you're not alone.
If you start a thread you'd like me to comment on somewhere, just post a link to it here and I'll follow that link. I'd be glad to help in any way I can.