Yuuri...you... [Actually unable to speak momentarily]
...I can't believe you. Wolfram-sama cares for you, a lot. Even if you didn't want it, you should have explained it carefully and made him understand rather than doing that! I wouldn't have been surprised if he'd hurt you after hearing that!
If you care about Josh as more than a friend, you shouldn't have just let it happen while keeping Wolfram-sama's hopes up! He probably just wanted you to care for him! Just...hoping that maybe one day he person he loved would actually return his feelings... [Having been in that situation, of loving someone who doesn't love him, he knows it hurts. But to be engaged...it would only make it worse]
I don't think you realise it, but you really are in the wrong here. You shouldn't have done that to him.