Comeoutahead,
People on this board see me as a pro-D, blunt type poster who doesn't hold back and part of that is true because of the nature of my profession, my betrayal over 20 years ago and the hardships I have had to face in my life but like ALL the other posters here, my intentions are always to help.
Some of what I will say has been said already but I wanted to reemphasize a few things.
First, kudos to the 4th post here by Lostmyreligion, one of the best posts I have read on this board. Listen to everyone's opinion. Absorb all of it and it looks like you are. Some people say take what you need and leave the rest but the biggest problem with that is that noone in your situation knows exactly what they need and they could change from R to D and back to R hour by hour. Getting out of infidelity is not an exact science so listen to all perspectives here.
A great poster, Crushed7, hit the nail on the head in his posts here.
A few preliminary points
1) Counseling is a waste with someone who is in the affair
2) DNA your child
3) Initiate a 180 and consider an in-house separation but also be prepared to call the police in getting OM removed if she tries to invite him over after doing this
4) It is not always the best to 'stay for the kids'. You could be destroying yourself by staying with someone who has no morals or compassion as evidenced by her affair so early in your marriage and the threatening of the family unit for her own cheating ways when your kid is only 16 months old. That is a special kind of 'fucked' up if you know what I mean.
Now, if I were you, I would do this
1) Open a new email address and create 6 emails and save on draft. This way, your notes will always be accessible but not saved on your computer. The 6 topics will be
Divorce
Separation
Ethics
Exposure
Finances
180
2) You need to attack on all 6 fronts simultaneously
Let's address each topic
Divorce. You say you tried this and it didn't work. You didn't try it, you threatened it and she now doesn't believe you will do it. Hard, cold papers in her hands by next week. See if your attorney can't draw them up by next Thursday and have her served Friday or served the day she gets another job. Because you forced her hand to quit the other job, she may be in a position to ask for alimony. Make sure she gets another job fast. However, you have not tried divorce yet. Hard filing. Chart your progress in your email drafts.
Separation. In house. Check the laws but do not leave the house. Change bedrooms, get a lock on your door and stand your ground. Also, get a VAR and carry it on you because you can't trust her at this point. Stop the counseling.
Ethics. Your attorney is all over the ethics issue. Good. Make sure you have the evidence. Create 5 batches of evidence. One for you, one for the attorney, one to hide in a location away from the house and one for the ethics board and finally one when you expose to scumbag's long term girlfriend. Make sure you file and do so through your attorney. Ethics boards will take it more seriously if it comes from a good attorney
Exposure. You must expose to the scumbag's long term girlfriend. As another poster said, he has a connection to her and she may be the AP of his last wife. He is not going to dump his girlfriend for your wife. Put yourself inside this guy's head. he is a predator. All you wife is to him is another conquest and your child to Mr. Scumbag is 'baggage'. He doesn't want to help raise a 16 month old who is not his. That would require work, receiving less attention and responsibility. He also knows your wife is a cheat and he will not hunker down in a long relationship with an adulterer. So the second you expose to his G/F, she will hand him his ass. Doesn't mean she will get rid of him due to income. Maybe she will. But he will surely drop your wife to save that relationship unless they are open relationship type people. However, expose on the same day you have your wife served the papers. Your wife will surely go to him for advice and he will be freaking out over his relationship with his girlfriend. Your wife will lose her 'two' men on the same day. Expect her to come back to you in a state of panic. You have gained control of the situation. That doesn't mean you will want her back. I wouldn't but at least you control the cards again.
Financial. This is a big one. There's going to be cost involved however in the end, it's well worth it. Take how much you think you will need to spend and double it, then try to find a way to raise/borrow such monies. You must do this and track it.
180. Someone already posted the link on this thread for it. Implement, while I know it's a long list, emphasize the most important parts of it. The 180 is for you to heal but sometimes it can be seen as revenge and I have no problems with revenge either. These people need to be attacked so they will learn from their predatory ways.
Again, keep notes and check your progress in each area and at some point, you will come out ahead.
I believe your wife has had an intense, long term affair with this dirtball and has lied to you about it. Time for you to put this fire out by all means possible