Travis....I had the exact same scenario last year. I read and watched all the advise on sheet mulching, and applied it to a garden i had no problems with slugs in the past. Well exactly as you said, it created a Horror Show. Last year i would pick off at least 100 slugs every morning.......All summer long... there was not end. I did eventually rip up all of the sheet mulching after i realized what i had created. I also have snakes, toads, and plenty of birds around......but they did not make a difference.
What if found was that d.e. did not work effectively. I carried around a plastic container with about 1/3 water and a squirt of Dawn dish detergent. I simply put them in the jug and they die pretty quickly. I could not stand to cut them up. After a few days the dead mess went into the compost pile. i dont mind slugs in the compost pile, and i noticed that the dead slugs did attract other slugs.
I also put out bug traps, which are juice containers, painted blue and with tangle trap applied. It basically catches mosquitoes, black flys, horse flies. When these are full of bugs i put it on the ground and in the morning... all of the slugs are on the container, eating the dead bugs, and not in the garden. They seem to like meat better than veggees. it has been by far the best slug trap going.
I live by the ocean and pick up seaweed which i wrap around the brassicas. They will not go past that.
As for the comment that it would have happened anyway.......I totally disagree..... the sheet mulching causes disaster in some areas. Obviously like mine and Travis's.
I believe the lesson in all of this is for each one of use to discern what works best for us and Not to listen to those who think they have the magic pill for everyone. Every situation is unique.
With my changes to the garden this year.. i only have about 10 slugs each morning...far more manageable.