What is wrong with my car? is it the water pump or something worse?

my 2003 dodge durango broke down 6 weeks ago. the mechanic put it on the diagnostic machine, and it said i needed a fuel pump and a water pump. well i got the fuel pump changed and he told me if i kept water in the car it could hold out for a little while until i get the water pump fixed. so i kept water in it it's been 3 weeks. saturday night all of a sudden i watched the temperature gauge jump to HOT! I pulled over and it was smoking like hell. i'm lucky a friend of mine drove by at that instant and went to his house and got me antifreeze and water and put it in the car. so it was fine sunday. then last nightafter i got home it was smoking again. i let it cool down and then filled it up with water. this morning i took my daughter to school and then drove to my other daughter's daycare and it was smoking like crazy and there was antifreeze and water all over the ground where i parked. so i left it at the daycare and got a ride to work. should i fix the water pump? or is