Rocco's Lymph Nodes are large

I'm not sure where to began. Last week we were told Rocco would probably live 1-2 months. One week on and is lymph nodes are getting bigger by the day. I think this week or next will be his last. This is very hard to deal with. One reason it's hard is because Rocco is not a old dog with chronic problems and pain. He is a happy 6 year old dog. He loves to tug every morning. He loves to go on his walks and eat. He loves to say hi and meet people. His spirit is indomitable. He's been through a lot. Being picked up as a stray. Spending over half a year in narrow concrete and chain link kennel at the old shelter. Getting giardia and mange there. He has been to the vet so many times. He's been stuck with needles all over his front and back legs, his chest, his jaw. He has been given toxic chemicals time and time again. If ever there was a dog that should resent going to the vet it should be him. Yet he is always happy and excited to go there. Not for needles or drugs but for every person who will even take a second to make eye contact with him. When I first got Rocco I remember taking him to my uncles storage unit. I took him there because the facility is fenced and I wanted to see what he would do if I let him off leash. I took the leash off and walked away from him, around the corner down row of storage units. I stopped and looked, he tentatively came around the corner and looked me in the eye. He then walked up to me. I knew then that Rocco and I had a special bond. He is my faithful friend and I his. I feel sick at what is happening. I have much trouble sleeping. I stay awake and think about Rocco. I can't take care of him anymore, only comfort him until his death. I know life is not fair and it just is what it is but I think this is bull shit. He is 6 years old and 2 of those years were living with cancer and 2 were spent in a shelter/on the street/living with people who most likely did not give a shit about him. A good dog like him deserves better. We should have taken him around class today for goodbyes. Don't know if he'll be back.