floor is collapsing.... I jump to platfrom on left...then to the next one on the right... now the platform directly to right of the one I am now on has already collapsed..(or is in the process of collapsing), no matter how fast I go... so, only option is to try to jump to the one further on in center of room but I cannot reach it.... what am I doing wrong??

ok .... figured out a way to do it.... but i am sure it is not the real way.... immediately turn back towards the door you came in by, then run to the left jumping on the collapsing bricks to reach the corner ledge now inch by the column and you are on the side passage, now climb up the stairs and go to the area where you jumped to the bells previously... now hang and drop in front of the exit door.... it will not open but if you go to the bottom of the broken stairs and hang off the edge... it works!!