I am so sorry to hear you have lost little Rascal
It is so heartbreaking to hear what you had to go through
I can only imagine how awful it is to lose a dog, they are real members of our families, and it sounds like your experience was particularly hard given that the vet didn't pick up on it earlier.
It must be painful to know your other dog is hurting, too. My heart is with you. Take good care and may Rascal rest in peace in doggie heaven