I’m sorry you’re feeling hurt rn, but yes, that was extremely insensitive coming from someone you consider a “close friend”. My close friends have known me since childhood and never ONCE have they brought up my stutter, or made fun of me in any way. They simply ignored it and loved me for who I am as a person. True friends would never make such hurtful comments. Period. Definitely take some time apart and hopefully he apologises GENUINELY to you. Voice your hurt too. Make him understand how hurtful that comment was. If he is a true friend, he will take it back and apologise for being so insensitive.