how do I get over the death of a pet

I had my cat Horus for 10 years I got him when I was 6. I had to make the decision of pittting him down because he was going through kidney failure. That was in October, it's been 4 months and every time I think of him I start bawling. I use to say goodnight to his ashes every night but now it's too hard. When I do muster up the strength to say goodnight bubby or something like that I can't help my self from getting his little urn and cuddling it until I fall asleep. How do I accept that he's gone. I know this isn't a "glow" question but I would really appreciate some help.