I worked with both Tamils and Sinhalese people and I can tell you that both sets did not hate me (being a Indian) but yes my Sinhalese friend did hate Tamils (but maybe he was a exception) I can not speak for everyone. Infact my Sinhalese co-worker used to give me lifts home in his car he was big softie at heart. (Although when I first met him he did ask me if I support the Tamils in Lanka lol) him being a big bastard I said I did not
As for the Tamils, I know many from Lanka and some who have been active in the war with the Tigers and the stories they told me about kidnapping while sleeping in their homes etc made them join the movement.
So for me I do not have a stance I just get both sets of opinions, I don't know why they hate each other and hope they can both live in peace.