Anna~
I can tell that you love your dogs and that this one means a lot to you.
While I also could not give up a dog that I had had for most of it's life, I would not criticize you for it or accuse you of not caring for your dogs and giving them the best lives possible.
Just so that everyone knows,
you are in good company in your policy of rehoming some of your females. Even
YorkieRose finds homes for her retired females so do not let these other members make you feel guilty for doing what you feel is best for all concerned.
Keep your chin up!