Thelma, {{hugs}}
I'm so sorry to hear about Charlie's passing, but never doubt that you did the right thing by him--he's not suffering anymore.
Also remember that you gave him a chance that not many other people would have. I know I'm not the only one who's put down a stray they found as soon as they heard it had FIV/FELV. You gave him a loving home and the best life any cat could want. Never forget that.