Devastated!

I just learned my 16 year old cat has cancer. I have had him since he was a few months old. I cannot tell you how much my heart hurts. He got me through my breakup last year by giving me a reason to get up every day. He listened to all my life-is-not-fair stories. He stayed in my lap while I cried over my ex. My ex used to complain about my cat all the time about me caring about my cat more than him. The thought of losing him is bringing me to my knees. I will try to treat him with medicine as long as his quality of life stays good. If he responds well he could live another year, maybe two at the most. I had hoped that he would make it to 20 years old. I did everything right - took him to the vet, bought quality food, etc. I know 16 is old for a cat but he’s been my buddy for so long. I want him to be healthy and live forever. I know it’s selfish to say this but I am still adjusting to being alone after my breakup and knowing what’s happening now is sinking me back into such a sad place. But I will take care of him as best I can and make him as happy as I can and pray I can make the hardest decision when it’s time. I can’t stop crying. And I have to go visit my family next week for Christmas and will be away a week. He doesn’t travel well and the vet said he would be best staying home with a daily sitter like always. I would stay home but my parents are in their late 80’s and I can’t do that to them. I pray he stays ok while I’m gone. Anyone have a cat with lymphoma and they did really well? My heart is breaking.