Hello Marko and welcome
What a sad tale!
I would say that, if your partner of five years is offering sex to old flames by e-mail, then you are probably better off without her ~ especially if it is because your business is going through a bad patch.
I'm not surprised that you are in shock.
There are at least two sides to every story, but, even if she had valid complaints, this isn't a good way to deal with them.
Remember that time heals.