I am pretty sure this was from Gintama but I may be wrong. I read a chapter where it was set in space, and there was a fat woman obsessed with making beautiful people ugly.

At the end there was a flashback of how she looked when she was young and she was a cute girl, and there was a dead? man sleeping in a coma or something.

I can't seem to find this chapter but then again there are 500~ chapters in Gintama...T_T

You know, it must be from the Ryugujo arc around chapter 174-182.

The guy in the coma was the one that woman was in love with, IIRC.

Whether we fall by ambition, blood, or lust,
Like diamonds, we are cut with our own dust.

It is, thanks! 🙂