Saw A Kingfisher kill a White Eye.

I'm very new to birding. Today I saw, for the first time, a bird killing another bird. It was a white throated kingfisher and it was killing an oriental white eye by repetititevely slamming it against a tree and then swallowing it whole. I knew, obviously, that birds do eat birds but seeing it just ... idk, made me very sad. I'd like to hear more from you about instances where you may have seen birds killing another birds and what you thought about it. Thanks!