The loss of a pet?

As an adult you would think I could handle this better.  I think because I am older it is harder.  I know that animals don't live forever.  I know that God has been at work in my life this week because I have had two substitute teaching jobs.  I say that is God at work because I don't think I could have been at home alone these past two days.  I really believe if I had been at home I would have driven myself crazy.  Every where I look I see my little Frito.  Her toys, her little sweater she wore when it was cold, and every time I look at the couch where she used to lay.   There is a big empty feeling in this house since she is no longer with us.  I thank God for getting me out of the house these past two days.  I also thank the teacher that called me.  I know I will get over this and some may say I am being silly.   I just feel like there is this giant hole where my little angel used to be.   I still catch myself reaching for her during the night in the bed, looking for her on the couch, and looking for her in her little bed.   I am an adult.  Why is this so darn hard?   Why can I not just get over it?  
When Mark and I were first married and we would have an argument of course I would get upset and cry and pout.  Frito would find me and want to lick the tears from my face.  That was the only time I would let her lick my face.  She would always help me to get over my mad spell.  She loved her toys.  When she was little we would have to hide her toys so she would go to sleep.    Usually that would take some time because every time we hid one she would go and find another somewhere in the house.  Her favorite treat was peanutbutter.  She only got a little but that was all she needed.    She hated riding in the car, but she would rather ride in the car with us than stay in the garage without us.