Ways of coping with pet bereavement.?

[Jules UK]

I had my beautiful, loyal 15yr old put to sleep yesterday & cannot describe the pain and loss I am feeling. She was diagnosed with kidney failure which came as such a shock on wednesday but I was told she would have 4 to 6 months left. On Friday she became unwell and would not eat so I took her to the vets yesterday were she was rushed to the pet hospital to be put on IV fluids supposedly till tuesday to try and get her back to health although she could not be cured. I left her for an hour but felt the need to phone up to check how she was and was told her kidneys have deteriorated a lot since the Wednesday and it was just a matter of time even with treatment that she would become very poorly. I always promised I would never let her suffer and would let her go with dignity so made the decision to go straight back and have her put to sleep. She was so releived to see us and desperatley wanted us to bring her home but we brushed her hair kissed and cuddled her and I held her in my arms as she drifted away. I was the kindest thing we could do for her and did not want to let her down when she needed us the most but i feel such a overwhelmly sensation of loss and keep thinking I can hear her around the house. I really dont know what to do with myself and wonder if anyone has anyway way of helping my son and myself cope at this sad sad time. Thank you x