It is so hard losing a long time friend. If you can, I would consider giving the love that you are missing to a new friend. It can ease the pain if you are able to care for another kitty. It would not be a replacement but it would be a reason to go on living. And simon would want you to help a cat in need, of that you can be sure. In the mean time, keep in mind that grieving is normal, it does take time and it will get easier.