First thing you can do is report the posts that you believe are harassing or abusive...as you have already done. It will then be up to a moderator to act, or not act, on your report based on their judgement of the situation.
You cannot block someone from seeing your posts.
You can block other people's post from being seen by you. Go to your Control Panel and look for Edit Ignore List in the column on the left. Add the other person to your ignore list and you won't see their posts as you read the forums.