it is hard when you lose a friend, but there is no need to be sad, when one of my babys passes away i have a burst of joy, happiness and privlage that i got the spend so much time with them, create so many wonderful memories and create moments that feel like they last a life time.
im sorry about your dog, all i can suggest is to give him loads of cuddles, kisses and talk to him and tell him how much you love him