Pat, you are amongst friends here - we all understand, especially those of us who have been through the heartbreak of losing our beloved companions
We treasure every day we spent with them, and in time, the pain eases and we can look back on all the happy times we spent together.
I do hope that you will feel able to open your heart and life to another Cavalier - I can understand you being concerned about the future, that is something we ALL have to plan for, no matter what our age - you don't know what tomorrow will bring - but there are many ways of planning for this, even if you don't have family who would take on a dog in the event of something happening. Most responsible breeders would ALWAYS take back a dog they have bred and either keep it or find it another wonderful home, equally rescues are responsible for the life of the dog and would also take it back - so please don't let that put you off.
Cavaliers are very adaptable - we like to think they would only be happy with us, but most people who work in rescue - and I from personal experience of looking after other Cavaliers and fostering - can assure you that they usually settle very quickly, as long as they are fed and loved!! They usually settle within 1/2 a day, the only one I know who took longer was a very "pack orientated" 3 year old male, who went to a home as an only dog, but with a very devoted new owner, and even he settled within a week!
I hope this reassures you a bit - and maybe you will make friends on here, even someone who would be prepared to help out in the event of illness or other problems.
Take care, and we hope that in time you will again have a wee furry body to cuddle.