wow, you poor love, what a load to deal with.
Definitely, no going to MC, no "working on the relationship".
The only thing you need to do right now is take care of yourself.
This is trauma plain and simple, it takes it's toll on your physical and mental well being. Please make sure you drink plenty of water, eat if you can (anything, it's all calories), try and sleep and take some walks, amazing how they help clear the head.
If you're struggling, please go and see your Dr, there's nothing wrong with getting a little something for the insomnia and anxiety.
IC for you can be very helpful, it's a relief to have someone impartial to unload on.
The other thing you must do, is get tested for STD's. Honey, everyone here will tell you how imperative it is. Don't believe him if he says they used protection, chances are, they didn't, and condoms aren't enough protection anyway. His activities are very high risk.
These are things to protect and care for YOU.
As for him, he's delusional if he thinks you have any part to play in HIS affair, or his recovery from it.
He's still in the affair, he hasn't ended it, he still contacts her. He must go NC for there to be any chance.
Unless he's a dripping, snotty mess on the floor at your feet, begging for your forgiveness and another chance, he's got a long way to go.
There are many great posts here for you to read, I'll bump as many as I can find, (many have a red dot) hopefully other members will bump some too. "20/20 Hindsight,What I wish I'd done when I JFO" is a great start, also pop along to the Healing library (in a box, top left hand corner of the page) and read about the 180. The 180 is your friend, especially right now with the way he's behaving. It's function is to make YOU stronger, more resolute and better able to make decisions based on your needs going forward.
As for him he's got some nerve expecting his betrayed wife to help him cope with the devastating results of his affair. He doesn't even have the smarts to drop her like a hot coal and try to even start to repair the damage he's caused.
Please remember at all times, that nothing you did or didn't do lead him to have an affair. This is 100% on him. If he'd put the same effort into his marriage with you instead of a string of OW, you would both be in a much better place right now.
I'm so very sorry you find yourself in this position, I wouldn't wish it on my worst enemy.
There's no room for three in a marriage honey, what happens going forward is up to you.