Emotional affair - what would you do?

Married 9 years. I’m in my early 30s. I have three kids. Just found out my husband had been having an emotional affair for over a year. What makes this even worse is that we knew a couple who went through this, this past year. So same time as my cheater. And I told him I thought it was disgusting what this guy did having this emotional affair. That doing that to me would be immediate grounds for divorce. All the while, he was in his own affair. So anyway, I saw a Snapchat notification and said oh who’s that? He pounced on his phone so fast I knew immediately. He lied all morning denying knowing her. So I got his phone and did some digging, found in Facebook messenger old messages how he thinks about her every birthday (they share the same one). He hasn’t seen this girl or talked to her, supposedly, since high school. Immediately after the hellos and how are yous, he goes right into bashing our marriage. A marriage I thought was great. Telling her he got married too fast. If he didn’t have kids, he’d be single. Talking about our children. He asks where she lives, where she works. Saying he’d stop by sometime. (Says he never did. Who knows). She’s also married, two little kids. He asks for her Snapchat and that was the last of the early messages I got to see. Snapchat messages delete after 24 hours so I’ll never know exactly what they talked about or did since that was the way they communicated. This was a secret Snapchat account by the way, we share his other one. So after the lying, and me calling him out, he finally admitted to knowing her and talking to her. Immediately blames me. I complain too much, how it was nice to talk to someone else (even though in her last snaps she sent, I did get to see because I had his phone, and she was complaining). He did say he’d tell her about our arguments. I don’t even remember any big arguments. Just petty five minute ones that blow over.
My post is too long. Have to break it up

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Continuing..
And we get along great so I can’t even recall the last one. Talked to her about how his family and I don’t get along. Completely out of context. I love his family and tried for years to be a part of their lives but they never treated me kindly and have nothing to do with our kids. Never even asked to meet my 18 month old. And my husband never stuck up for me all those years his family would belittle me and be mean. So call me crazy, I asked the man I married to have my back.
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Which he never liked the hear. Said I can stick up for myself. In a twisted effort to comfort me, he says, this ‘other girl’ usually took my side. If my eyes could roll any harder, they’d be rolling across the room. I don't know what I’m even doing writing here. I’ve never posted a thing in my life. I guess I just needed to vent because I have no one to talk to.
Emotional affair - what would you do?
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