Husband of 3 years has had 3 year affair-devastated

[wishiwas18]

I'm new to mumsnet and wanted advice. I found out a few weeks ago that my dh has been having 3 year affair. He's left and moved in with her. Already!
I know I should be trying to come to terms with it but I'm heartbroken. We have teenagers who are coping quite well I think.The thing is we were in trouble and had talked about separating but I didn't know there was someone else. How do I get my head round this?
He seems to think because we'd discussed separation that "I need to move on". We were married over 20 years. I'm all over the place. One minute I feel quite strong and at others I'm a wreck.
Please help.

Where is Mr OW?

It's not being a saddo to miss him - he was a part of your life for a very long time, so it's inevitable that you will feel that "gap" very keenly, however irrational that might seem.

Go easy on yourself :)