I Miss My Dog

I was informed today the convocation day is on this wednesday, when I am going to get my HND certificate. It's not yet the degree, just the 2nd year. We are going to have another one in next year when I am actually getting my degree. I know I am supposed to be happy, but I don't feel like as our family dog died on this October 30 at about 1.50 PM. How I celebrate this event when I lost someone whom I loved dearly? How I am supposed to be happy when I have this guilt that I could have done better to ease his pain or perhaps save him? However, I know I am supposed to be happy, because I know he will return to me one day after reincarnating. So I should be ready to take care of him once again.