Whatever Xinlu wish for has come true

I think it means that Xinlu got to see Ilay being devastated over losing Taeui because Taeui chose to go with him the moment Ilay comes to rescue him. Xinlu's hatred for Ilay is much deeper than his love for Taeui. He doesn't really keep Taeui because he loves him but just to win over Ilay. So in a way, Xinlu already got his revenge on Ilay.

That's the gist of it if I am not mistaken. I read the explanation several months ago (=・ω・=)