There is a big black blob on my screen that grows daily.

So, about 6 moths ago, my macbook fell and the screen cracked from the inside. I took it to get it looked at, they told me that the only thing that got messed up was my screen and that i should replace it with a new one as soon as possible, there was a tiny black blob on the left bottom corner, now it has taken over 60% of my screen and it keeps growing, the funny thing is that the blob moves from side to side, if i postpone getting a new screen is it possible that it may damage other parts? And they are charging me 800$ to fix it, is that too much?