Fisherman I am so so sorry, I lost my aged dog 3 years ago and it still hurts. It may be worth getting an autopsy - it may certainly reassure you there was nothing you could have done - at least talk to your vet. Some kind of memorial is an outlet for grief - believe me so many understand, talk about your grief to others, in the UK we have an animal bereavement charity it is such a huge issue, you are not alone my thoughts are with you 😔
great quote Millie btw too