[limey]

Hey, ThatGuy! Well done for treating your friend/wife's best friend like a true friend. She's in a difficult position, and I commend you for not using her to get back at your wife, and for respecting her space and not going round to have it out with your wife.
I don't have any helpful advice. I do remember how painful it was being dumped by my then fiance, who'd apparently been working up to it for months, and deceiving me increasingly about his feelings over that time. My reaction was that if he'd made that decision then I'd never be able to change his mind, and if he'd made that decision without my input then I didn't want him back, no matter how much it hurt to lose him. It hurt more than anything I'd ever experienced but I was determined to get over it. And I did, by waiting it out.