Seller lied about mold in the walls :-(

[Archer Stone]

We bought a condo and moved in 5 days ago. Me, my wife, and 1yr old daughter

Inspector had found a small amount of mold under the sink in the inspection. Less than two square feet. Sent it to a lab and it tested as “penicillium,” not dangerous.

The seller said “it’s just on the surface” and wiped it away with bleach.

I insisted several times that we should cut into the walls to check, but the sellers kept saying it just was a tiny bit of mold so unnecessary. I checked with the mold lab and they said “the seller is probably right, its just a small amount and it’s not the dangerous kind, it’s not worth the trouble.”

The broker (supposed to be loyal to both sides and truthful and honest) sent us an email saying basically “it’s not a problem, we are not cutting the wall.”

Well, we negotiated a “buyers credit” for $1500, closed the deal and moved in last week. 

Today I met the neighbor who shares that bathroom wall with us. Apparently she’s been staying in a hotel for weeks because it’s not livable in her apartment because of health problems from black mold!! She said it was too expensive for her to fix, so they’re just gonna clean the bare minimum and it’s gonna keep coming back

Apparently the backstory is: a few years ago an upstairs neighbor (now long gone) had a fight with the HOA, so they turned on the taps and stuffed tshirts in the sinks to flood the apartment and caused water & mold damage in the downstairs apartments.

What the actual F

We have a baby in here and we spent 90% of our savings to buy this condo, all cash. We have very little savings at this point

What would you do? Can we sue the seller or broker to cover costs of fixing it? I have emails from the broker with strong implications saying that the sellers said this is not a problem and it’s just a surface thing and it’s not in the walls.