Step 2 - Schedule an appointment with your doctor ASAP and get a battery of STD tests. Firstly, he may have had a different OW previously. Secondly, you need to consider the likelihood that OW has her teeth into more married men than just your husband. That’s very common. Potentially, you’re sleeping with him, he’s sleeping with her, and she’s sleeping with several men, and they all have wives. That’s a pretty wide net. You’re need to get tested as a matter of priority and stay away from him.
As for everything else - I’m sorry. This is what happens when you are stuck with a mid-life-crisis, affair fog, middle aged partner who chooses to blow up your family. What they say and what they do is often poles apart.
Just stay the course with DBing, it’s your ticket to happiness (whether that be alone, or back together in 5+ years).
And don’t beat yourself up. These people are master manipulators and liars, and you’re just a normal, trusting human being.
If you really want the best chance of OW getting cut off, you’d be wise to throw him out on the street, put all his possessions on the curb and change the locks. But very, very few people have the conviction to do that.
