How do I help him

a man I have known for 5 years has just told me he has bone and liver cancer and been told he has 6 months to live he wants to die alone has 2 sons that don’t care and a sister that is too busy for him . Rob has been trying to marry me for 5 years we dated for 2 days then he lets me down by backing off . He rang me after 2 years of minimal chat to tell me he is alone and will die on his own in pain what do I do am I selfish not wanting to be involved in his last few months