ok, so... My opinion might shock some of you (argh help me).
This is your DH's sex life. This is his sexual character. This is how he gets by with having a platonic relationship with you. No sex with you. Home, kids, food, and I hope some kind of affection for you.
The opportunity and absolute 24/7 accessibility of online conversation and connection, that can so easily be taken to meeting up and having sex with a stranger, is just so available and so easy. He's found that out. He doesn't sound like this is the first time he's spoken to someone.
It's like free prostitution (for both women and men). You can have a sexual connection, conversation, meet ups if required. You can just have sex once or for a longer period of time. It doesn't have to be in person, it can be just in conversation and if required audio/video.
It IS horrendous because it means that any partner or spouse can pretty much have multiple sexual encounters outside the marriage and keep it secret.
The only benefit I can see is if someone doesn't meet up but just somehow gets their sexual source of love from this virtually, preferably without video or calls, and that means they can stay in a mutually sexless marriage but still be a good partner and parent in all other ways.
I am so very sorry, OP. If he's willing to go and meet a woman then that's not good at all. it's one thing talking, it's another thing meeting in real life.
Ideally, the talking wouldn't even happen.
I don't think you should confront him. It doesn't sound like he'd react well.
Do you want to just stay as you are, with your husband, marriage and home, and carry on as if this wasn't happening?
Or you get rid of him.
But getting rid of him, as you probably already have thought, is such a massive thing as then you and the kids are on your own.
I am afraid to say that you might be best just trying to leave it be. You know this now about him. It's a bit like a live version of porn I suppose. He's there for you and the kids but this is his sex life. I know that's not how it should be. It is all kinds of wrong. But it is how it is.
I am so sorry that your choices are all challenging. But for now I think I'd just give yourself a bit of time to come to terms with it, to let the shock die down, and not stir it up any more.
I'm sorry OP. Love and hugs to you. If it is any comfort, probably half the husbands (and possibly wives) on here are most likely secretly doing something more or less like this.