I would'nt be NICE to her, I would reccomend you be CIVIL
Are you NICE to children when they misbehave too?
I understand you are worried you may scare her off, but believe me its NOT likley helping you.
Just be a STIRLING example of ADULTHOOD, you don't have to be NICE when she's being distant, just be CIVIL... think Mr Spock... he's not nice to anyone, but he is civilized and responsible...
Keep in touch with her family, keep showing them how adult you are... they will turn around too...
Your wife has likely poisoned you against them... you need to make HER look like a FOOL... you DO that by acting like a mature responsbile ADULT around her family... they will gradually SEE who is lying to them and they WILL INFORM you if they see her cheating...
Build ALLIANCES as MUCH as you CAN
And yes it looks like you have the idea, get RIGHT in the FACE of that affair.. affairs are FUN when they are secret and no one knows... they are NOT FUN when EVERYONE knows and you are the subject of GOSSIP
Keep exposing that affair, make it look like the most HURTFUL SELFISH thing anyone could ever DO... by YOU acting like an ADULT, SHE looks BAD.. THAT is how you WIN over her family and eventually HER as well...
Once she's clean, and her family likes you... THEN you can decide if this is what you want...
Renovate your home before you sell it so to speak, you may find you don't WANT to sell it after you fix it up anyway...
