I'm avoiding a person I'm pretending to be friends with because I can't stand him as a person
Is there a special reason you can't stand him?
No, I just think he is an asshole.
If you think he is an asshole then it's fine if you don't want to spend time with him. Spending time with a person you dislike would be miserable.
I still need to be friends with him, maybe I will refrain from talking to him.
It sounds like you are using this person for a reason. That is messed up. If they found out they would be devastated by your reasons.