I'm disgusted by my employers

You agreed to do adult laundry. I'm sorry you didn't consider what it would entail.

As someone who has paid for someone else to do my laundry, if I had to separate out my underwear and anything else especially dirty, then what would be the point of someone else doing my laundry? I'd still have to do it myself.

At this point you have two choices:
1. Tell your employers that you realize you would prefer not to do adult laundry and will accept a potentially small pay cut for that change.
2. Find a new job.

It may be a vent, but when you get things together realize that you will need to a bit logical about this.