The chance of being refused boarding is close to zero. Most likely the agents will not even notice it. A good argument would be that you flew the outbound segment - then of course you are able to travel on the ticket for the return segment also.

I wouldn't try to get this sorted out now. It will only draw attention to the spelling error and anyway, you will have to pay a fee for any reissue of the ticket so it going to be expensive. Rest assured that you will be able to fly on the ticket as it is.