Tom Sandoval Is in Love with Raquel Leviss, Says Tom Schwartz

Tom Sandoval's affair with Raquel Leviss has moved into the "love" category ... at least, according to his friend and business partner Tom Schwartz, who's spilling a TON of tea about the Scandoval.

Schwartz finally opened up about the messy relationship drama Wednesday night on "Watch What Happens Live" ... telling Andy Cohen he knew the 2 hooked up way back in August, but thought it was a one-time thing.

That is, until January when Sandoval dropped the L-bomb on Schwartz.

He says his buddy admitted he was in love with Raquel -- something Schwartz was mostly shocked by, but not completely ... adding their "emotional affair" was sort of an "open secret."

Fans have been wondering why Schwartz didn't fill in his friend Ariana Madix about the sneaking around, and he answers that question, too -- putting the blame squarely on Sandoval.

TMZ broke the story, Sandoval and Ariana split last month after she found explicit messages on his phone, and it's been a whirlwind of drama ever since.

The "Vanderpump Rules" cast filmed a reunion where we're told things got heated ... and fans everywhere are dying to see it all unfold.

As we reported, Schwartz was pretty quiet for a while but spoke out for the first time last month ... remaining firmly on the fence in the fallout between his friends.

Sandoval shared some of his thoughts last week, BTW.

He kept things pretty vague, but noted his businesses with Schwartz have definitely taken a hit in response to the scandal.