FANS who watched the season finale of the “Real House­wives of Orange County” were shocked when Vicki Gunvalson’s son-in-law unleashed a vicious verbal tirade against the mother of another housewife.

But The ENQUIRER has learned it’s not the first time that U.S. Marine Ryan Culberson – who’s married to Vicki’s daughter, Briana – is alleged to have verbally abused and bullied a woman. According to court records obtained by The ENQUIRER, a woman that Culberson dated for four months in 2010 was so afraid of him she filed for a temporary restraining order.

ON THE AUG. 5 EPISODE OF “RHOC,” Ryan exploded at Lydia McLaugh­lin’s mother, Judy Stirling, during a party at Vicki’s house – because Judy had put her feet up on the couch. Ryan, 29, who lives with Briana in Vicki’s home, repeatedly cursed out the 65-year-old and told her “get the (bleep) out of this house.”

That was likely no surprise to Rachel Lawrence, 28, who claimed in her Request for Order for Protection that Ryan stalked, terrorized and verbally assaulted her after they broke up – claims Ryan denied. The two later entered an agreement – which expires this month – in which Ryan promised to stay away from her, and each promised not to contact the other. She agreed to withdraw the request for restraining order as well as a complaint she filed with the USMC.

Now, a source says his explosive nature has the “RHOC” cast and crew on edge.

“Everyone on the show was shocked and disgusted by Ryan’s behavior,” added an insider. “People are scared of him. No one knows what will set him off.”