Don't feel too bad. Yep, rookie mistake, but one that many, many, many people make. You are not at all unique on that score.
For what it's worth, you can probably limp along for the short term (after, of course, fixing the sway issue) with the set up you have. But be aware that it might not be fun going on long trips, especially through the mountains, and your truck will wear out faster than you might expect.
But wait, there is a bright spot here: that's a perfect excuse to GET A NEW TRUCK!!! Yea!!!!!!!! Who doesn't covet a new truck?
