I'm so sorry

Rufus is lucky to have such a loving owner and I know it must hurt so much to see him like this, and to have to let him go. But it's the most loving thing you can do for your little guy, so that he's no longer in pain

My heart breaks for you!
No one knows when the right time is to get a new pet after losing one. You'll know when the time is right, follow your heart. A new companion will never replace your Rufus, but may help you to smile and lessen the pain just a little bit (I speak from experience). BIG hugs to you and your little man