Honesty is the best policy. However you do want to be clear that the ultimate decision was (yours) to make. Ultimately people do what they feel is in (their) best interest. A good or great friend will understand that you doing what you feel is best for (your) marriage.
People often ask can men and women be friends. There is usually a debate about one person wanting a relationship with the other. However I have always pointed out that even if the two people involved are strictly platonic friends like (brother and sister) there is always a chance that their spouses or significant other are not accepting of the “friendship”. This is another reason why the (men and women as friends) often does not last for eternity.
Given the choice of building a life with someone you are “in love” with or maintaining a friendship…. Most people will choose romantic love over platonic friendship. There are others who would insist that you force your spouse to accept your friendship. After all you may have known your friend before you met your spouse. The truth is there is no “right” or “wrong”. There is only “agree” or “disagree” You can't make someone like something they don't like nor can you expect to accept things they don't want to accept.
Both of you are (entitled) to have your own “deal breakers”. However if something means less to you than it does to your spouse why go to war or possibly risk them deciding to move on.
We may choose our actions but we cannot choose the consequences of our actions.