I feel your pain Richard1966
I had a 12 year old Black Lab who had been with me since she was a pup, and we really loved each other. She was diagnosed with the same thing, and I was given the same options.
I thought about it overnight and the next day I took her to the vet for the steroids. For a good month, she was her old self and we all enjoyed her as much as she enjoyed herself.
Then one day, she just suddenly no longer wanted to move. I carried her in my arms to the vet, who was very good and compassionate. I stayed with her until the end and the vet took care of everything afterwards. I still miss her, but I shall always remember her last month of happiness, rather than that of the suffering she would have endured.
I hope you make the best decision for your set of circumstances. No matter what you decide, you will hurt for a long time. It has been ten years now and I ran across her lead the other day, and I freely admit, it really hit me hard.
My thoughts and prayers are with you
Old Salt