Why can't I get it right??

Why can't I get it right??

I just cant get my mac and cheese to stay together and its really getting me annoyed.
This is what I do.....cook the mac until soft ..drain it then run cold water through it and put it aside while I make the white sauce. When the sauce is cooked I take it off the stove and stir in the grated cheese (I usually use Edam but have tried it with Cheddar as well). After combining the two tog I place breadcrumbs and more grated cheese over the top and place in oven. Now comes the part that drives me up the wall. when I remove it from the oven ..the sauce has separated (curdled).
I have tried not blending the cheese into the white sauce instead I have mixed it in with the mac then poured the sauce over ....nothing works!!!
Any idea's please...... what am doing wrong:confused:
Have you ever tried doing layers of grated cheese, kind of like lasagna, instead of cooked sauce?
Basically...do the same with pasta, make several layers of grated cheese with a top layer, etc. and bake it.

OR you could try not washing the mac with cold water after you are done boiling. I usually don't.

I usually do the dry grated mac and cheese in layers instead of the cooked sauce, so I don't know if it will work for you or not. :)
Nearer to God and Pastor Gary thank you for your help on this problem. I will definately try both of these during the next few weeks, thanks for taking the time to respond.

Blessings to both of you. :)