This post is not selfish. It is completely understandable. I wish you comfort, your situation is not something anyone other than you can truly understand. I would say that  love is unique and can never be replaced or replicated. Your husband will love you in this world and the one beyond and that will never change. 

I don't think that you are selfish, I think that you have the right to your feelings, just as we all do.  I have stage 4 cancer, but I feel the exact opposite of how you feel.  I have told my husband that I want him to find someone else as I don't want him to be alone in the world.  Some people would perhaps say that I am 'wrong' or 'strange' for telling my husband this, but as I said, we all have the right to our own feelings.  Maybe it is not my place to say this, and I apologise if I am out of line here, but I think that you should try to enjoy the last weeks, months or years that you and your husband have left, and let the future take care of itself.  He will always love you, no matter what, and even if he does meet someone else after you are gone, that doesn't mean that he will stop lovong you. Take care, xx