According to sources with direct knowledge, the model frequently complained about the pop star getting physical with him during their six years together.
The sources tell TMZ there have been numerous fights where security has had to step in, but in one instance there was no security in sight, reports aceshowbiz.com.
There was allegedly one occasion where the singer gave Sam a black eye while he was sleeping. She reportedly flew off the handle and began punching him. Despite the alleged shocking attack, Sam reportedly did not strike back, but was stunned as his wife pummeled him.
The alleged incident went down early this year, around the time Sam was photographed with a black eye and bite marks on his forearm. When paparazzi noticed the bruising and asked him about it, he tried to play it down and asked photographers not to shoot him.
As for the cheating allegation, Sam reportedly believes that Britney hooked up with at least one male staff member at her house. The 29-year-old allegedly learned about the infidelity because he found footage of the staffer and the 41-year-old singer together in a compromising position.
Sam additionally claims Britney asked one staffer to shoot video of her naked.
TMZ further reports that the 'Womanizer' songstress is in a fragile and hyper-sexualised state, which has contributed to her dangerous decision-making, making her a risk to her own safety.
While Sam has been acting as Britney's support system for a long time, her recent conduct reportedly was the last straw, leading him to file for divorce.
In his first statement since the split news, Sam wrote on his Instagram Story: "After 6 years of love and commitment to each other my wife and I have decided to end our journey together. We will hold onto the love and respect we have for each other and I wish her the best always."
He added, "S**T happens."
His representative Brandon Cohen, meanwhile, has denied claims that he challenged the prenup.
"There are many claims that Sam is challenging the prenup and threatening to exploit his ex-wife with videos," the rep said in a statement issued to The Hollywood Report. "However, all these claims are false, as no negative intention has ever been directed towards her and never will be. Sam has always and will always support her."