while i understand how you feel and support it (i've also known people like that, and still do), i think now is the time to try and focus on the positives and make the last remaining few weeks/ months, or however long he has left, bearable

i know that sounds hard because of how you feel about him, and it does sound a horrible, horrible person. but i'm sure you can think of something.. something he's done, or a good memory you have of him

positivity is the key to helping him now, and i believe no matter what the circumstances, you can find some positive memory etc
try not to be bitter towards him. i made that mistake before, and trust me, i learnt when it was too late.