Oh dear. This makes me cringe because there but for the grace of God, go I. But in my case, the ruinator is my spouse. I beg beg beg my spouse to let me and ONLY ME do our laundry because of what he calls my "excessive special needs" clothing. But alas, he insists on being "helpful" and these are the kinds of outcomes I am terrified will happen (and sadly, have happened).
His sorting is minimal. He never checks pockets, so all sorts of odd things in his pockets have been washed (chapsticks, pens, nails, plastic bags, leaves; I NEVER put anything in a pocket so any things found in the dryer come from him. Melted chapstick is a nightmare, BTW.)
I cannot get him to understand that items in mesh bags MUST be hung to dry, for instance. Plus, he puts everything in the dryer on the hottest setting for the maximum time. And then he takes the items from the dryer and crams ALL of it into one laundry basket, which of course results in massive wrinkles. He doesn't like to fold, so that is my task. I'm not sure why despite my literally 15 years of pleading on this he continues to disregard, but that's how he rolls. When I point out items that have been ruined, he gets mad at me for having "so much stuff that requires special treatment." My argument is how hard is to learn the rules or to just let me do the laundry?
I have friends who say I should just do separate laundry, but because it's just the two of us, it seems hugely wasteful to do multiple tiny loads once a week.
I hope your pants can be salvaged or replaced.