Despite numerous attempts to defuse the tension, the relationships aren't getting any less complicated between “The Real Housewives of Beverly Hills” Season 5 cast as they continue their Amsterdam vacation. Last week, the group sat down for a dinner that ended in a glass-breaking shouting match between Lisa Rinna and Kim Richards. Things didn't get much smoother in Tuesday's episode 17 installment, as the ladies, yet again, attempted to have a nice meal -- although this time, the glassware was spared.

In episode 17, viewers were given a glimpse into Yolanda Foster's struggle to live with Lyme Disease. The 51-year-old was forced to spend a day in bed while the other ladies headed out to see Amsterdam. Later that evening, in an effort to make up for the missed day, Yolanda arranged for the group to have dinner on a beautiful boat. Unfortunately, the serene setting wasn't enough to keep tensions among the ladies at bay. After an explosive cocktail hour, the housewives were able to make it through their meal. Things took a turn for the worse, however, as their boat ride came to a close.

Just before heading back to their hotel rooms for the night, Brandi Glanville and Lisa Vanderpump, who had been getting along until this point, got caught up in a discussion about “The Love Boat.” That conversation quickly led to playful shoving. Then, it happened: Brandi reached out and slapped famed restaurateur Lisa Vanderpump across the face.

“No, that's wrong,” Vanderpump said, holding her cheek. “I don't like that. It's like throwing a glass of wine in someone's face.”

Fortunately for Brandi Glanville, none of her fellow "RHOBH" cast members were around to witness the incident. They were, however, watching her strange behavior play out on TV last night, and many of them had a thing or two to say about the slap.

Lisa Vanderpump, who was recently named “woman of the year” by the California state assembly, kept her thoughts on what happened between her and her former friend simple. Her first reaction was simply, “Ouch.” She then took some time to reveal to fans how low she had felt Brandi had stooped by hitting her.

While Lisa Vanderpump opted to play nice, Kyle Richards seized the opportunity to fire back at Brandi for calling her a hypocrite in a previous episode. Her tweet also touched on a near-brawl between the pair, during which Brandi threatened to punch Kyle.

Lisa Rinna, who has had her own issues with Brandi this season, held nothing back while watching the episode. The actress joked about being “#Amsterdamaged” after what should have been a relaxing, fun trip.

Brandi Glanville has not yet addressed the slap. Tune in next Tuesday to "The Real Housewives of Beverly Hills" at 9 p.m. EDT on Bravo to find out if Brandi plans to apologize for her actions -- and whether or not Lisa is willing to accept.