I'm appalled and flabbergasted at the treatment you received by the veterinarian you trusted. I think that what you experienced is getting into the way of your grieving process. I hope you get somewhere with the complain you filed with the
Ontario College of Veterinarians.
None of us who care for our pets would do what they are accusing you of - and it is pretty obvious reading your post that you loved your cat very much. Please know that you did the right thing by not letting your cat suffer. That is the biggest act of selflessness one can possibly do! It is easier said than done of course, but know that the vet is lying to you, and probably because you were one of the few (if not the only one) to bring their absolute unprofessionalism to light. I'm glad you have a dog that you love very much too that is giving you a reason... may the two of you take care of each other and I really hope you will be able to process your grief despite everything else that has happened.
“Until one has loved an animal, a part of ones soul remains unawakened” ~ Anatole France