A Night Out Leads to Unexpected Flirting

INTEGRITY...
My best friend and I have been close since high school.
We have been threw alot together over the years. Helped each other out threw the years.
Some time last year he was saying he wouldnt fuck with any of our friends wives or exwives.
My wife and him get along great. And flirt alot. He was my best man in our wedding 10 years ago. She is my second wife.
My wife and I are closeted swingers. No one knows. But we play when we go out of town. We never wanted to play with friends or local for fear of someone finding out.
My wife is quit good in bed. She knows what she wants and gets it.
When my friend ( Adam) told me he would never fuck a friends wife last year. I mentioned it to my wife. We laughed because Adam is a playboy. Trying to fuck anything that breathes.
We laughed it off and I told her he couldnt turn her down if he had a chance.
That was all last year.
Fast forward to last month.
I was out of town for a few days. Adam knew it.
My wife went out drinking with girls from work for happy hour. She ran into Adam at the bar. They talked. She said he was glued to her hip all night.
But she said it was the usual flirty banter between them.
She said he was more touchy/ freely than usual and he was throwing her hints. But she ignored his advances.
She called me the next morning telling me, he was hitting on her but not crossing the friendship line.
We laughed it off.
She called me a few hours later. Saying he called her. Asking if she wanted to go out for dinner and drinks, since I was out of town and she might be bored by her self.
I told her to put him to the test. And if she wanted to fuck him. Have fun. But dont tell him that I know.
I got up early and went home. I got home about 1pm. She was still in her nightgown . Not very motivated.
I asked what happened. She told me to wait till she showered. I knew something happend.
She said they went out. And she intentionally didnt flirt, so she wasnt leading him on.
But after the 3rd drink he was pulling out all his tricks. They went to a bar and had a couple more drinks. They danced and he couldnt keep his hands off her. They decided to leave to go to another place. In the car. He kissed her. She said at that point. She was going to fuck him.
But he was trying to get her to blow him in the car.
She said she started sucking as he drove to the next bar.
She said she stopped sucking. Set up and told him to take her home. He panicked thinking she changed her mind. But she told him he was going take her home and show her how good of a fuck he was.
She said that put the pressure on Adam to perform.
They got home. Tour each others clothes off. Ended up on the couch . She said he was very good. Made sure her orgasms came first.
They were done with round one. Got in the hot tube. Started again before getting in our bed. He fucked her all night. She said he left at 5 am.
Fast forward about a week.
I went with Adam to move some furniture he was buying. He was stand off ish. But talked.
I told him I thought my wife had cheated on me while I was gone. He tried telling me she would never do that. I shouldn't believe it. Blah blah blah.
I couldnt keep a straight face.
He was so quiet. And hes normally a chatter box.
We spent the afternoon getting the furniture moved. Started drinking beers.
We set down on his new couch and I brought up his conversation from last year. Asking how much integrity he really had. He wouldnt say a word. Changing the subject.
Finally I asked if he would fuck my wife on his new couch. I started laughing hysterically. He knew he was caught. Got all mad and defensive.
He calmed down. He wouldnt stop apologizing.
I told him the story. But also told him it wouldnt happen again.
It's only been a couple weeks.
Havent seen him since.
My wife is now saying she would fuck him again but with me included.
Well see how this works out.
What are good friends for?