What the NEW black hole discovery tells us!

One of the most perffect things to prove Einstein GR correct is found at The BULLET CLUSTER some say so lets dig a bit into see the bullet clustter a bit: they say that the size of the BULLET CLUSTER is 3720000000 LY size;  -  Look for the 2 mayor light spots in the picture, one is found up right front facing picture and makes a perffect (a)form as it s light hits the pink front part, the (a) form is bigger than the bullet form, size while the dark ring of the other light spot  found at midle- bootom next to the bullet form and makes a round dark circle as it hits the front pink part. 

My question is  that if I take the size of the (a) form I would fill the 2 clusters with maybe 40 times the (a) form so how could it be that if they say that the front pink part belongs to the 2 clusters that colaided into one another making the size of 3720000000 light years????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????