Light Yagami was a fucking fool for wanting to dispose of Misa once she served her purpose. This is a lady who halved her own lifespan no less than two times on Light's command and gave up killing innocent people just because he told her to. Misa pledged her love, life, and loyalty to the wrong man.

Not that I completely feel sorry for Misa. Because she never expressed any remorse for murdering innocent people. In fact, she had enough evil in her heart to start killing innocents after learning a shinigami had sacrificed his own life to save hers. You have to be very cold-blooded to do such a terrible thing. And yes, she did stop killing innocent people, but only because Light commanded her to, not because she had a heel realization of any kind. She wasn't sorry for any of it at all.

So, in a way, Light Yagami was her punishment. God allowed her to fall in love with a man with liquid nitrogen in his veins. Misa Amane totally deserved this guy.