I know you've already had enough tears for this -
But are you sure that you rinsed that top thoroughly? I am wondering about that CLR being destructive to the fabrics?
I have also washed an unquilted top - one of my cats peed on it. I pressed it from the back and the top and then the back again. That was definitely a challenge. Then I laid it on the ironing board and clipped the threads row by row.
I have also learned to not use anything I consider iffy as to durability. I am in the wash-before-cutting group, so if I get a bleeder, I will not use that either. (It goes in the waste basket if I am unable to return it - I will not put it in a donation pile for some other person to have a headache/heartache.)