Best friend since grade school is crossing lines with my wife

My best friend of 20+ years has always been a ladies man. He gets it, always will. He's help me through rough times and I have helped him through his. But lately when my wife is around at events were both attending he's either to drunk to know that his flirtation level is way up in the disrespect category or he doesn't care that he's distancing our friendship by doing so. He has a fiancé thats really passive about all of it and pretty much everything he chooses to do. He has confided in me about his infidelity on multiple occasions which leads me to believe I shouldn't trust him at all given that and the way he has acted around my wife. Its coming to a head real fast.

It hurts on a lot of levels so I've just been focusing on my passions and my marriage with my wife. She is loyal, beautiful, so much fun to be around. I understand why men are attracted to her. Its not a big deal when its a stranger. Its passing comments at bars that are mostly incoherent. But this situation with my friend is not as easy to navigate. I've been with my wife 7 years / 3 + married and I don't want to have to tell her my best friend is crossing the line because its always been a common knowledge between my wife and me and the rest of our friend group that he's just naturally flirty with everyone he comes in contact with. He left a get together one night and the last thing he said to my face was "I wanna fuck your wife" smiled and walked away arm in arm with his fiancé....whom, obviously heard him. I told him to go fuck himself. Drunk? Most likely. But I never figured out the right route to take with this. Should I talk to my best friend of 20+ years and tell him what I think about the situation or tell my wife first? I'm teetering on telling my wife because I want to strengthen the trust and vulnerability in our marriage but I also want to set my friend straight and make him realize the error of his ways are costing our friendship. (SIDE NOTE) My ex left me for a good friend of mine going on 10 years ago so its bringing back a lot of baggage from the past that I thought was buried. I don't want to feel jealous or untrusting in my marriage and the situation with my ex was much different and a very much a young love scenario. Whats your suggestions on how to approach this? I need to make a decision I just want some honest feedback first.