Emotional Affair??

I need to vent and get some advice. My husband and I have our ups and downs like any couple. Sometimes I give him a hard time about going out drinking - although I shouldn’t because I usually go out once a month with girlfriends. I always say the difference is I’m going out with mutual friends - all of whom he knows. He goes out with coworkers who I have never met. Long story short he’s been going out with coworkers more frequently lately and even one day recently went out about 3:30 pm and came stumbling in around 11:30 pm- never once reaching out to me that whole time. I told him it bothered me and we moved on. He’s been out a few more times since then and I just couldn’t shake the feeling that something wasn’t right. So today I find Facebook messages between him and a female coworker - very flirtatious messages and some even late into the night - midnight. I confronted him and of course he said she was just a friend who has helped him get through a hard year at work. I told him he’s having an emotional affair and asked him how he would feel if it were me doing this. He also admitted that he had deleted some messages bc he knew I’d get mad. I am crushed and my world has been flipped upside down. We have a family and I don’t know what to do. Please any advice from someone who has maybe been there? I’m feeling so lost right now.