You have to engage with some at work who you do not like today, but be polite and keep it professional.
Today you have to deal with someone you do not like and this can be difficult for you, but try to keep a good solid line between business and pleasure and recognise why it's there. You may have to engage with this person, but you do not have to be their friend. These lines are there for a reason and will keep you on the side of professionalism. Be polite and civil and get the job done.