I have a W with a similar EA. I'm 99% certain it would never progress from what it is now - ' good friends' according to W.
But she gets something out of it.
For instance before BD on her way home from work in the car she would ring me. Now she rings him.
I know him and since BD have met him twice. Since two weeks he is also a FB friend of mine. We have had a 30 min conversation in the last 2 weeks. He is funny and engaging but but He has mental (bipolar) and physical problems and W has a history of befriending life's waifs and strays and taking them under her wing.
So a non-typical EA , a neutral person W can talk to. I asked whether she had spoken to him about us, she admitted it, but said she wouldn't do so again.NB she hasn't told her best friends other than ' we are having problems'. I also value her integrity. She has never lied to me in 15 years.
So what to do. MWD says pick your battles. Is he a threat? Yes but the same as if she was talking to a best GF.
I feel like talking to him directly - I know where he is working and could meet him for coffee
Me49 W45 T15 M13 S11 S8 BD 11/15/11 & 3/27/12 Moved out 4/9/12 Moved back 4/23/12 W working on US 5/20/12 Now Piecing! May-Oct14 drifting Dec 14 W agrees to more QT BD Oct15 ILYBINILWY W filed 1/25/16