Why Would Assad use Chemical Weapons?

Though it seems insane to us here in the Western World, we are not living the war every day in Syria.

This is what I think is happening. Though Assad and the high leadership of Syria might escape the Rebels, most of the Alawite and minority populations in Syria will be murdered or abused by the Rebels. This is likely true because of the torture and abuse of Sunnis by  Assad and the Alawite minority leadership in Syria.

Using Chemical weapons would be a way to kill as many rebels and rebel sympathizers to allow more Alawite Syrians to escape Syria. So, it would be used as a smoke screen knowing full well any Alawites would surely be massacred by the relatives of any rebels left alive after the chemical Weapons were used. So, I see it as an escape smoke screen for the Alawite leadership, which seems kind of crazy in itself.

But, here is another angle. If chemical weapons are used the United Nations and NATO will come in and establish order in Syria very likely. What would happen after that would be anyone's guess as to whether a Somalia like place would exist and be fairly lawless or whether something like we see in Libya as a new but still unsure democracy would be established?