[name_f]Antonia[/name_f] an-TONE-ee-ah
There isn’t a correct English way to say it, in a sense, because it isn’t an English name (it’s Latin). So the rules that apply should be the rules of a Latin name. It’s rather bizarre that your class is emphasizing the EE sound. I just checked behindthename and in six languages - including English - the TONE sound is emphasized. They are just saying it wrong. 