Hello Mishy,
I am so sorry to hear about your dog, and I can empathise with you completely. Even after losing my first B&T who I had for 15 years a few years ago, I still miss him, still get a pang in my heart wishing he was here.
He was old, and it was his time and we looked at one another and we both knew, and in that meeting of eyes we said our goodbyes. That moment I will never forget and I will carry that and all the happy memories I have of being together, from the first day I got him, until the last, and it's the happy times we had that make things a bit easier for me.
I also remember Sam, he was beautiful and stone deaf his whole life but so full of fun, he was never sad dog, no matter what was wrong with him. . Even when his heart was so enlarged, the vet said she didn't know how he was still alive, he sat on the table and still wagged his tail and gave kisses to everyone. He died the day after the treadmill test at the Cardiologists, but again, we are happy we had him for the 6 years we did, he brought us so much pleasure, with his quirks and wonderful personality. We are very happy he died with us at home.
These are the two Cav's we have lost in the past several years, they will never be forgotten and although we now have 5 others between my mum and me, they don't replace Sam or Raistlin because each dog is irreplacable to us.. they simply carry on giving us their own wonderful memories which will also live with us when they go.
I know it's hard now, I honestly do, and while time is a great healer in all things, it might help to realise you wouldn't be "replacing" your lost Mishka. If you went for a rescue Cav, you would be helping that dog recover from ill treatment and misery and giving it the love it might never have with someone who obviously has a lot of love to give.