答案是broke.
解析：短语break down 可以表示“（机器,车辆等）坏了,发生故障”或者“（身体健康/精神）垮掉,崩溃了”.
而根据 went to work 可知要用一般过去时,break的过去式就为broke.
比如还可以说：His health broke down after the death of his wife.
"在妻子过世后,他的身体垮掉了."