Around a year after this started the guy was married and moving abroad
She told him she has feelings for him but wont cheat at a wedding I was with her.
6 weeks later it was his farewell party, she made up an excuse and we never attended.
The next day she was crying, in bed, messaging friend on how sad she is etc etc and she sent him a farewell message telling him how wonderful he is, he understood her like few others , his wife is a lucky woman, she loves him and will miss him terrible.
1 month later she downloaded 12 self help video on how to save a marriage after an emotional affair.
You'll probably never be able to get to the bottom of this, but it's possible that this was a physical affair and not just emotional.
Also, it seems that their relationship developed alongside his relationship with his now wife. This is odd. I wonder if his now wife knew anything about this then. But although that happened, he married her. It could be that your wife's feelings were much stronger than OM's, and her seeing this is why she lashed out at you during that time. She made a fool of herself, and that's embarrassing for her to realise. And since then, the feelings she has had for him have continued to affect your marriage.
It's going to be hard for you to recover if you don't know the truth. You need to have a short period of time during which she tells you what happened during the affair, and when you can ask questions. You need to know this man's name and where he lives now (we would hope that he is still abroad and married, and that physical contact between them hasn't happened since he left, and would be very difficult now). You need to know whether there is any online or other non-physical contact, and if there is, she should be very willing to stop it. (I'll bet she has followed him on social media on and off). She should be very willing to let you have the means to check on her online activity now and in the future - passwords etc.
Once you've got the basic facts about the affair, and you have the assurance that she isn't following him or in contact with him in any way, and that she wants to work on the marriage, if you want to rebuild the marriage all discussion of the affair must stop, forever. If you bring it up again and again because you're hurt by it and you have doubts, this will harm your marriage and keep the affair ever present between you.
These are hard requirements, especially for you since you've only just found out about the devastating affair and are now questioning the basis of your entire marriage. I suggest you read all of the free materials on this website that outline the steps of recovering from an affair, and give them time to digest. Start
here.
Finally, posters on this site have found marriage counselling to be often useless, and sometimes detrimental to recovery, and this seems to have been your experience. The one good thing about it is that your wife has been willing to do it. You should seize on her willingness and take the opportunity to counsel with Dr Harley directly. He is the founder of the Marriage Builders programme and this site. He will email with you and your wife (for free) for as long as you need it, and he will talk to you both on the radio show. He will convince your wife about the need for honesty about the affair and transparency going forward, and he will not make her feel defensive.
There is more advice we can give, but I'll stop now and give you a chance to reply.