What did i do

Im an emotional wreck. Im angry sad hurt bitter depressed and i feel like everything is spiraling even more out of control. I cant handle his ups and downs on my own anymore. I have one friend that listens to me and all she says is leave him. I have no family this is my last option. My boyfriend of nearly 3 yrs has cancer. Before i met him he gave up on treatment shortly after falling for him he decided that he was going to go back for treatment. As i mentally and emotionally prepared myself for some of what was to come he decided some time that he wasnt going to treatment. One day he is all excited making plana for the future telling me to make appointments with this doc or that one then the next day im calling back to cancel. He has me on an emotional roller coaster. He says we are going to get married then when we are supposed to go look at rings he says he dont want to get married cause he is liable to die the next day. I dont bring up this marriage crap although it would be nice to cling to his name when hes gone. His family is constantly starting drama and i blame them for his lack of wanting to fight his cancer. HES ALL I HAVE AND HES SO WILLING TO JUST DIE. He doesnt even want to try to beat it.