Obviously you are just jealous of him because of what your boyfriend admitted but that thing is already a past and your boyfriend chose you. What they had now I believe is totally a friendship type of thing and not the same thing that he has with you otherwise your relationship would not last for five years or so.
You cannot just take away your feelings of how you hate his bestfriend but you should try to be more civil towards him. If you are asked to come along with your boyfriend to hangout with his bestfriend just try to consider going.
You cannot just take away your feelings of how you hate his bestfriend but you should try to be more civil towards him. If you are asked to come along with your boyfriend to hangout with his bestfriend just try to consider going.

