Hi
I can understand how you have got yourself so wound up about this, but try to look at this from her angle.
She looked confused. A man she is normally at the least friendly with exploded at her, swearing and telling her to stay away from him. To add to this, his wife shouting too. From your earlier posts it would not seem that that is the way he has been behaving - he may have not been answering texts etc but he has been working with her and I think I remember something about a lunch or similar away from the gossip.
If he is her senior and has had an inappropriate friendship (or more) with a junior, he can not lie to her and sideline her. It is not professional, and I think it would be harassment.
She is probably contacting him as she is now worried that he will be doing the sidelining again. This will get him into trouble and reflect poorly on your husband. Nobody is irreplaceable.
In the work context, it does not matter whether people get on, they like each other or if frankly they have been married and split up, they are generally expected to continue working together in professional way. So while he can stop the non work chat, he can not insist she stays away from him at work on professional matters.
I would bet there is somewhere a woman, slightly confused and very worried about what tomorrow will bring.
Your husband has caused you this hurt - it sounds like she backed off when she found out you were pregnant, read into that what you will about what happened before, and I suspect your husband has picked up the friendship again. Has she behaved perfectly - probably not - but she has not behaved as badly towards you as he has.
Fwiiw I suspect that this was/is some soft of emotional affair, but my interpretation based on her confusion, his pulling away and unusual explosion that this was more him than her.
Not sure what to advise except please don't let yourself approach her again and look at your relationship closely.
Hope you are ok.