Thank you all for replying - it's helpful to see the different perspectives.
I maybe should have said there is no chance of an affair because he lives 1000 miles away, and also clarified that he was a good friend in the past as well as a colleague. It's not impossible he's looking for an emotional affair. I believe what he says about his relationship - to me a lot of little details add up to things not being right.
@user64332 not a digeridoo, but congrats to your DH on his musical versatility. His wife seems to have almost no tolerance for his playing (upstairs when she is downstairs - no idea if directly above) but of course I only have his word for it.
@NotMyPremium Absolutely, I'd believe a female friend. I agree I need to be less available though.
@AmberItsACertainty thanks for sharing your experience with your friend - it feels very similar to what's going on for me, and your advice about getting away before the crying starts is very sensible.
@AlternativePerspective thank you, I think it could easily be both. He doesn't seem to have anyone else to confide in and I do agree it's so hard for people to speak out about abusive relationships. I have encouraged him to speak to a professional, I wish he would.
@bombastical I don't think it's lies but you are right, the behaviour towards me is starting to feel controlling.
@Wanderlusto vulnerable narcissist is starting to sound right...
@Onthedunes I'm not sure how I suddenly became the bad guy... yes I have become too involved but my intentions were good. I've seen photos and videos of the house with him in them. I've heard a lot of little details that sound manipulative to me... not being allowed to leave the house alone sounds pretty bad. I meant that he would be alone 'at first' because if he leaves he'd move away and she'd have friends nearby. Hopefully he'd subsequently meet people and become less alone.
I think it's true about people reconnecting in the last year - I’ve also heard from university friends who I hadn’t been in contact with for years, my husband too.
I plan to follow advice to model good boundaries and step back a lot, and appreciate the warnings that he may not be all he seems.