Missing My Baby

My baby Tigger passed on March 15th, I am lost, hurt and unsure of how to feel. I feel like his death is my fault because I was the one who had him put to sleep. You see Tigger was 17 1/2 years old and he was both FIV positive and had diabetes. In the last week before his passing he had lost his appetite as well as weight. He also became dehydrated and both his white and red blood cell count was out of whack and continued to drop very rapidly over the course of 4 days. They also found that he had something pushing on his liver and stomach as they were out of alignment and the liver did not look normal. When I asked my vet if he had a 50/50 chance he said no, I then asked about a 25/75 and he said he really didn't think so.

I have cried a river of tears and I am now telling myself it is my fault and I cannot stop thinking that there was more I could do, was there? I don't really know but should I have taken more time to find out? I feel like I let my baby down. I miss him terribly and want to hold him and kiss him so much.

My other issue is that my husband was promised the he would have the ability to get a dog once Tigger left me and this world. Now that he has he wanted a dog and found one that he wanted. What could I say? I have no excuse.... so we as of today have a dog and I hate it. I feel like the dog is intruding on Tigger's territory and I don't like it. What should I do? I don't think I am ready to have another pet yet because I must grieve for Tigger.

Can anyone help?