If you were me what would you have done about a hamster named Momo?

two days ago my brother was experimenting with my gerbel Momo and it bit him when he was taking him into his bathroom so his first reaction was to throw it down a set of spiral stairs and Momo sadly had every bone in his poor wittle body crushed to and shatered in every way emaginable and but some how he managed to survive the intial fall and layed at the botom of the steps making a WEET WEET noise and i was so sad i heard the fall so i rushed down the stairs and i saw him in the mangled state he was in and i just couldnt take it i didnt want to kill him but he was going to suffer and i didnt know how to do it my brother recomended flushinng him like a gold fish but i said no so i just let him suffer and die out ..... now that i am thinking about it what should i have done...? should i have let him die...? over the past coulple days i have almost gained a pound in a half cuz i eat when im sad and my dad and brother called me gay.