I miss you Aristotyle

I just lost one of my very best friends yesterday. Aristotyle (Arri) was my 10 year old Brown and Black Tabby. He was lost due to complications from Lymphoma disease. The diagnosis was unclear even after various blood tests, x-rays and an ultra-sound. Watching him go downhill slowly for the past three months has been very hard. I was searching and scrambling to try and figure out what was wrong and how we could fix it...until there was nothing left to be fixed. Our Vet tried to treat different symptoms with medications; Never being able to figure out what the root cause was.
Aristotyle was truly a One of A Kind Cat - he had more Dog traits than Cat, actually. He could play fetch (I mean throwing a beer bottle cap and having him bring it back to you and at times dropping it in your hand, or right by it) and did so from the time he was a small kitten until just before his passing. He would growl (like a dog) every time the doorbell rang or there was a knock. He would watch out the windows waiting for me to get home. My Fiancé would say that it was almost as if he knew the sound of my car...or just sensed when I was near - so unbelievable, I think...for a CAT!
Arri was so close to my heart that it aches so right now. It sounds weird, but I miss him so much right now that I actually can't wait to see him again on the other side...ya' know? As many pet owners can relate; Arri was with me through some pretty tough times and I always told him how Thankful I was that he was there, but now I feel like I let him down because I couldn't save him! I feel so terrible for all the times that he would run up to me and lay down in front of my feet to get some Love and I didn't stop to give it to him because I was too busy...what a guilty feeling! I hope he forgives me for that.
I feel bad for everyone that has gone through or is going through what I am at this time.
Thanks for Listening