I do think you should shred/powder the mimosa, and use a MUCH smaller dosage, in order to avoid fearing for your life...
And I wouldn't recommend 175g of caapi per person, not in the slightest, unless you REALLY REALLY knew what you were getting yourself into.
Try 100-150g per person, and maybe 3-5g of shredded mimosa bark. That's still likely to be an utterly ridiculous, world-rending, ego-shattering experience, but at least it's one that shouldn't kill you.
The above guys are right, there are a thousand threads covering this, check out the sticky in the ayahuasca subforum. I still wouldn't recommend taking a dosage even as high as the one I mentioned for you first time... but as I said, at least 150g and 5g won't kill you, even if it takes you for the ride of your life.