general problems of the 1997 Ford Windstar

I own a 1997 Ford Windstar, over the course of a month my husband and a few friends used my van to go hunting. Over the course of that month his friend weighing in at 300 pound sat in the center rear seat. The seat belt snaps into place on the side of that seat. During that month of getting in and out and plopping down on it, it broke and now I have to replace it in order to use it again. But im afraid that if it could brake because someone sat on it then how easily could it break during an accident. Please take the time to do an in depth investigation of it before someone is involved in an accident and the seat belt breaks and someone is hurt or worse killed.