Oh Nigella he's done plenty.
Put the shoe on the other foot. Could you ever imagine yourself having a flirty, emotional affair via text and email on and off for 7 years? No, I didn't think so.
This is all one big mutual ego boost. Probably no physical affair because that would be "wrong" in their eyes and they don't want to be seen as the bad guys. It serves their own purpose to keep it all on a fantasy, what if level. That way, they can still have their private thoughts and in jokes but they keep their families, cosy home life and reputations.
It stinks, it truly does. For 7 years, your husband has been fantasising about another woman. Not some out of reach celeb or porn star, a real life woman who reciprocates his feelings.
I would bet that their general plan is to wait until all the children are grown and then run off together into the sunset to live happily ever after. Fantasies and nonsense.
As I said previously, get your finances sorted before you confront. He's had 7 long years to mull this over. Who knows how much he might have squirrelled away.
He's done something alright. He's treated you like a fool Nigella. Sorry to be so harsh.