first, my prayers for you and your brother, and all the famlies involved.
my pregnant sister was killed in a crash that crippled my mother and scared my other sister's face (on thier way back from my then fiance's bridal shower). my wife's niece was just hospitalized after being in a fatal crash about two weeks ago.
second, it will hurt your score a lot. how much, no solid answer. fico is so fluid that what drags me down 100 points could cost you 50.
it could also end up in a judgement, garnishment, and leins which are other things that will hurt more.
how many attempts have you made w/the bank? how high up the food chain have you gone? maybe contact the local consumer reporter and give the bank a chance to get the choice of good pr?