Oh bless you OP. I am your age and divorced. I am also a lawyer.
Take things one day at a time. You won't be able to do everything you want to. Just do little bits, and praise yourself for anything you do get done.
Make sure you eat frequently, even if it's only a little. Don't drink alcohol, or if you do, don't buy much so you can't drink much. Go for walks to get fresh air.
Ignore the cleaning and so on.
Tell whoever will support you, he doesn't call the shots on what you do now.
Get a solicitor asap.
He's shagging the girl isn't he. Let's be realistic. He's only admitting to what you have found out. There will be more.
You will be ok. In the end. I enjoy it now and I'm glad I don't live with him any more. I do regret my family being broken up, for the sake of my kids. But that's on him, not on you.
Take it a day at a time.
And any difficult questions, consider in deciding, what is easiest for me?
And look after yourself. People will think he is an arse. Because he is. But they will go along with her m, because that's what people do.
They will respect you more. For not being an arse.