Damn, that Slade Wilson is a lot of fun!
Slade made it pretty clear on Arrow Season 2 Episode 18 that his idea of making Oliver suffer is a little different than what one might have expected. He's not necessarily interested in overtly killing people, but in sharing his truths with them. I like it!
On Arrow Season 2 Episode 17, it felt like there were just too many lies and they were at the heart of all of the hurt going down in Starling City. Slade may not see things the same way, as he's using truths to hurt those who love Oliver, but in the end he's probably doing Oliver a favor.