Purchase Contracts: Verbal/Email Purchase Contract Enough to Enforce

My question involves real estate located in the State of: WA

I've been working since February on buying my first home from a family friend who probably has 10 million in single family investment homes. Now the market is a buying frenzy, he's slowing selling off his properties. I got prequalified, had 3 CMAs done, we agreed at $175k.

Now he says we never agreed to anything. He put it on Zillow and is selling it to another cash investor for $210k. (Pricing the middle class out of homeownership)

I even have an email from him with his email signature spelling out our deal.

Can I do anything?

Purchase Contracts: Verbal/Email Purchase Contract Enough to Enforce