Just Lost Pet

I just found this site when desperately trying to find some people to chat to after losing my beloved cat Sammy on Monday night. After being ill for 2.5 months with heart failure we had to have him put to sleep and it was such a hard decision. We have nursed him every day giving tablets, all the stress that goes with that, the ups and downs as he got better then worse, better then worse and then to have him put to sleep was the final blow. I am trying to tell myself I have done the right thing but feel so guilty - would he have got better? did we do everything we could? Deep down I know we did but that doesnt help knowing I could have had him with me longer - selfish I know.
I feel like my heart is literally gonna break I am longing to have him snuggle up to me and lie next to my pillow like he used to every night. I have been through this before with my family cats but never my own, my own responsibility apart from anything - he was like a baby to me and I cant believe he is not here anymore. I know the pain will ease but that doesnt help me now. I am getting married next week and what should have been such a happy and exciting week is now far from either of these things. I even feel selfish for thinking that.