Such a tough decision but if you have family that will take your beloved pet then why not?
Another thought would be to become a rescue foster Momma! they would certainly love to have someone to count on. I know in my local area the rescue groups are always looking for someone to take on a momma cat and babies or even bottle feeding babies that have lost their mom. So many possibilities. I applaud you for taking such consideration!
My mom is now 71 and we she rescued her beloved Brady and is so happy to have him and she couldn't see living without another cat when she lost her last one.
Having said all of that most rescue groups would not want an outdoor cat for reasons you gave in your original post.
Tabitha April 10, 1995 - August 23, 2013
Bomber April 10, 1995 - July 12, 2010
Winston Nov 15, 1999 - September 15, 2011
Sophie Aug 30, 2011
"UNTIL ONE HAS LOVED AN ANIMAL, PART OF THEIR SOUL REMAINS UNAWAKENED"
He is your friend, your partner, your defender, your dog. You are his life, his love, his leader. He will be yours, faithful and true, to the last beat of his heart. You owe it to him to be worthy of such devotion.