see in Ontario, Canada it doesn't matter if you owned the house before you got married, the matrimonial home is always split 50 - 50 unless you can prove circumstances where that would not be fair, like you were married for 48 hours like Britney Spears and I believe you cannot contract out of that either in a prenup, though I imagine in some divorce settlements it ends up not quite a 50 - 50 split for the sake of moving on.....
My feelings on divorce where one spouse has an affair, whether husband or wife is guilty. The guilty one should have minimal entitlement to any marital property.
When I caught my wife cheating, I gave her a $1,000.00 to get out and that was all she got and deserved, and she agreed as she took it wih no problems. Of course she made the guy she was having the affair with, marry her within a week of the finalization of our divorce.