Unsure what to do

Me(M34) have been married to my wife(F35) for 6.5 years. We have kids, house, suburban life, right? So we’ve been in a bit of a spat for quite some time. We get mad, cool down and talk about it. Today it came to a head. We had some words, no yelling, and I tried to give her space the rest of the day. I had made a comment while we were arguing about a friend(M42) of hers that’s she’s known for a while. They haven’t seen each other in person for as long as I’ve known her but they’ve kept in contact every so often. Well, yesterday she was texting one of her girlfriends who is single and wife suggested this guy, out of the blue. He then sent wife a pic of him from the gym. Unfortunately for me he is her type to a T. The comment I made was the she got this look in her eye that I haven’t seen in a while, she brushed it off and I let it go. Fast forward to this evening and info on my nightly walk, the head to my friends house for a drink and cigar. come home and I can hear her on the phone, I wait and listen then hear her say his name. Wife didn’t notice I came home as she was in the bath and I barely made it to the bedroom door, fml right. I go back out to walk; I’m fuming, confused , distraught, you name it. I finally came back about 20 mins later and as I walk in she is walking to the kitchen, nothing on, while talking to this guy. She quickly tells him in home and hangs up. I don’t ask about it and go take a shower. After the shower I asked her how her night was and she said boring, watched tv and took a bath. She then acted weird the rest of the night. Then she just went to bed. No good night,even when we would have fights in the past we would always say goodnight.

She doesn’t know I overheard her. What do I do? Sorry for the rant, I feel so lost.

Edit: I confronted her, she didn’t deny anything and confessed that she wanted someone to talk to. She showed me the messages and texted him that I knew. He was persistent but she shut him down and blocked him. We talked it through and are going to work on the root issues of our marriage. Thanks for all the comments and insight. First time posting and really happy to have the Reddit community.