Not an answer as it's not what you are asking to do: I wouldn't talk to him about it. I've been in a very similar situation to you, and I recommend these things to help you overcome it: First, try to be happy that your friend found someone they're happy with. Second, reassure yourself that them having a partner makes no difference to your friendship with them. Third, write down all your feelings, maybe in a letter-to-your-friend style, to air them out. But don't send the letter. Destroy it or maybe put it in an encrypted file. Fourth, try to continue your friendship as usual. It worked for me. —
Sumyrda 22 secs ago