“Seeking Sister Wife” star Garrick Merrifield was arrested Monday for domestic violence against his wife … and now we’ve uncovered explosive details on the dramatic incident, including a threat to call Immigration and Customs Enforcement.

According to an affidavit for arrest warrant, obtained by TMZ, Garrick’s wife, Larrana, told police her husband snatched her phone during a heated argument, refusing to allow her to contact her family in Brazil.

The docs say Larrana informed Garrick she wanted to call police, but he wouldn’t give her phone back, and he threatened to call ICE. Larrana told cops she was terrified because she isn’t familiar with all the laws, even though she’s in the country legally on a visa.

He is in a plural marriage with his first wife, Dannielle. They have three older children together and they legally divorced years ago so Garrick could marry two other women … both from Brazil.