I see where you've misread what I wrote. Let me iterate first on the steps then explain what you got wrong here.
First:
Quit your job.
Block your AP on every available channel.
If she hasn't told her husband, tell him yourself.
Tell your wife if you haven't already.
Go find another therapist; A good one and toss yourself into IC to figure out the personality weaknesses that you have (and judging by your posts, there's more than a few).
Give your wife space; help her find a good IC.
Open up every device you have and make sure you are 110% visible to her.
Learn to be a safe partner.
If you have kids; start making up for the time you stole from them as well.
Now. The second part.
You misunderstand the advice given to you here. No one is trying to help you to "save your marriage". Your marriage is over. You torched it.
You lied, cheated and abused your wife. The sooner you realize this the sooner you can actually take responsiblity (which you're currently avoiding like the corona virus) and start healing.
All the advice here is to help you get on your way to try and fix yourself.
You invested precious time in your affair partner and now that's gone. None of it was real to begin with. Two broken people playing at being in-love in order to avoid facing the reality of their own shit. Again, you're not a snowflake. We've all been there. Same feelings, same excuses. All the way down to feeling like we've known each other for years even through it was four months at best.
The support you need is a reality check. That's my experience. That's why I came here and why I read every goddamn post by people who were betrayed by assholes like me and you. I want to know how they feel, I want to undertsand my wife better so I can be a better person.
Compassion isn't kissing your ass telling you it's going to be ok. Compassion is understanding exactly where you come from. Accepting that that's who you are right now and telling you that you can be better. But you gotta put the effort yourself and it's going take you a looooooong time before you learn.
So:
Why haven't you quit your job already?
Does your wife know?
Does your AP's husband know?
Have you gotten checked for STDs?
Have you blocked your AP yet?
Are you looking for a therapist specializing in infidelity?
What are you doing to stop being a liar, cheat and abuser?
And the list goes on. Grieving over the fantasy is part of it but it's a small part of it given the actual nothingness that you really had with her.