"This pps will dwindle all the way back down to .001 with [us] now owning only 1/500th of the shares we had."

After the split with 9,900,000 shares outstanding at 0.001 the market cap would be $9,900.

Before the split with 5B shares outstanding at 0.001 the market cap was $5,000,000.

A fall in total company value from $5,000,000 to under $10,000?

Let's assume the market cap holds at $5,000,000 (what it was pre-split).

5,000,000 / 9,900,999 = about 50 cents a share.