Rehoming a beloved family member is probably THE hardest thing a person ever has to do (even harder than putting one to sleep) because you keep thinking you failed. But nothing could be farther from the truth. Waffles WILL be happy by the sounds of her new home! And isn't that what it should be all about? You loved her enough to give her a different kind of home, and I bet that she will flourish.
We have seen the same type of things in the rescue of cats. A cat that had litter box issues in one house was perfect in another. Sometimes they need something that you cannot give (through no fault of your own)
Of course you are sad, you just lost a good friend, but NEVER feel like a failure!
{{{{{HUGS}}}}}