"He put 'acts of infidelity.' What does that mean?" Tamra asked Watch What Happens: Live host Andy Cohen.
"That sounds like he's alleging that you cheated multiple times in the relationship," replied Cohen.
"Is that what you got out of it?" she asked.
"Yes -- acts of infidelity," he answered before Tamra denied the allegations.
In addition, Tamra said she learned about Simon's divorce filing by reading about it online before being served.
"I texted him and I said, 'Infidelity? What are you talking about?' He had no answer for me," she told Cohen. "Unfortunately, I think he knew that [claiming 'infidelity'] would spread like wildfire and it's unfortunate."
"He's hurt, he's angry and he did that just to, you know, make a statement.... I feel bad, I wanted to keep it private, but once he did that it's no longer private."
Tamra told Cohen things had been "very hostile" in her household and culminated in a New Year's Eve argument that resulted in her prematurely leaving the home the couple is in the process of selling and moving into a two-bedroom apartment.
"I think my husband was very hurt when I left," she said. "I left the house knowing we had three weeks left in our current house because we sold it. Things were very hostile in our household and [come] New Year's Eve we had a blow up and I decided that I can't continue 2010 like this. So I chose -- which I thought was very brave -- to leave."
"I told him it's a trial separation," she added. "If things don't work out then we go our own ways but if they do then when you have to be out of the house you can move in with me and we can make it work."
Later in the live broadcast, Simon sent Cohen a text message requesting he "ask Tamra about the 200+ phone calls over 12 months with her ex-boyfriend."
"Wow, well first of all it wasn't 200 phone calls -- it was 125," Tamra replied.
"No, seriously," Cohen asked.
"That's what he's accusing me of [as] 'acts of infidelity' -- because I had communications with an ex-boyfriend," Tamra said.
"And was there anything more than communication?" asked Cohen.
"No, swear to God on my children's lives," she replied.
During the appearance, Cohen also asked Tamra if the couple has a prenuptial agreement.
"No, no pre-nup. We had nothing when we got into this [and] we have nothing going out," she said, alluding to the couple's recent financial problems.
The couple has three children together -- 11-year-old and 4-year-old daughters and a 9-year-old son.
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