Walter White is dead
Think about that for a minute. Let it soak, let it permeate your brain for just a moment.
Walter White was a respectable chemist who contributed to work that eventually procured a Nobel Prize for the benefactors of this research. Co-founded a company that became worth literal billions of dollars. Started a small family in a respectable town living a decent life with this same caring family, teaching the subject he loves the most.
And then he died.
Walter White started dying when the cancer diagnosis was presented to him shortly after his 50th birthday.
Heisenberg started to turn into an entity of its own. One could argue that his cancer IS Heisenberg, but I digress.
Heisenberg is cold, calculating, deceitful, ruthless, egotistic, greedy, all things Walter White is not.
There are many factors at work here, there's Walter attempting to provide for his family, Heisenberg wanting to become top dog, Walter wanting to live innocently, and Heisenberg wanting his accomplishments known.
In that bar watching that broadcast is what finally killed Walter White.
His family is in ruins, his money is worthless, his legacy destroyed.
Heisenberg is all that remains. It is all that he can be, and ever will be from that point forward. And Heisenberg is pissed.
He wants his money, he wants his family, he wants his empire.
While Heisenberg can never have Walter's family, he can be sure that his family is taken care of. He can be sure that Skyler now knows the true Heisenberg. He can also be sure that no one will ever make his product ever again. And that is what really mattered to Heisenberg, that everyone knew his name, that everyone knew he was behind his product, and that his legacy lived and died with him.
After all this is Mr. Chips to Scarface, and we all know how that ended up for Tony...