his behaviour in the office is further harassment. go back to your manager, express that you feel he is harassing you further by his behaviour and request that they do something about it. is he threatening you directly, or do you feel threatened indirectly? if you get no redress, go higher up the management chain (via a union rep if you have one) and make sure you make a note of every incident - time, date, place, behaviour, words, people involved etc. many people do not document problems properly and this can result in cases being dismissed/failing.....good luck x