My FI's Best Man has been completley uninvolved in both their friendship and the wedding. We are getting married in 3 months and the BM has taken zero interest in the wedding planning, bachelor party planning, or any of the BM duties. They have known eachother for years and years, and he is renting our spare room. After he moved in a few months ago, he completley shut himself out of our life, not wanting to hang out with my FI or have "guy time" or anything else friends would do. He pretty much plays video games all day/night, works, and disappears for days without saying anything to us.
That being said, my FI wants to have someone else as his Best Man. He doesnt know how to go about doing that since it is probably going to be a messy situation. Our wedding is in 3 months, and he has decided to have his brother in law step up (was his other choice before he even asked). How should he go about addressing this with the current soon-to-be-EX Best Man??