Janice, I have been there way too many times myself...It never gets any easier
I also feel that twinge of guilt each time, wondering if I did the right thing at the right time, but if you do it for them (and not for you), and with love, it is always right. We just have a hard time letting go when that time comes. But knowing that he is finally free, healthy and happy on the other side, makes it a little easier. Know that he is still with you tho in spirit.
You will also know when/if the time is right to get another furry companion. Some people get one right away and others need time in between before getting one, and then sometimes the new furkid will just show up in your life when you least expect it!
Sending healing thoughts your way for your broken heart!