You can remove the stitcjong with razor blade by JUST touching the stitches, but it is easier to do with small
(28mm or 18mm) rotary cutter. Hold like a spoon and gently touch the threads while pulling the layers apart gentlt!!
Try it with some scrap pieces firdst, A caveat tho: you will have to pick out threads from both sides of your piece as it only cuts not pulls it out as you rip. Good luck and let me know if you perfect the technique.
I have done all my unsewing this way for years and it goes so fast that I do not mind picking off the threads.
It really is a lovely quilt and well worth the time to do over.