Singer Casandra “Cassie” Ventura, a former girlfriend of Sean “Diddy” Combs and central character in the case against him, took the stand on Tuesday as the high-profile federal trial of Combs entered its second day in lower Manhattan.

Ventura, who is eight-and-a-half months pregnant, is expected to testify against her former partner for several days.

As Ventura was questioned on Tuesday, prosecutors sought to portray Combs as someone who was controlling and abusive, and who exerted power over nearly every aspect of Ventura’s life – including the clothes she wore, her career, where she lived, which escorts they would hire for her to have sex with, and who she could talk to.

Ventura testified that “there were violent arguments” in her and Combs’s on-and-off again relationship that spanned more than a decade, which she said would “usually result in some sort of physical abuse” such as dragging and kicking.

When asked how often Combs was violent with her during their relationship, Ventura responded: “too frequently”.

Throughout her testimony, Ventura teared up or took deep breaths, dabbing her eyes with a tissue and placing her hand on her pregnant stomach, sometimes rubbing it gently.

Early in her testimony, which began at about 11am, Ventura was asked to describe Combs’s “freak-offs”.

“It basically entails the hiring of an escort and setting up this experience so that I could perform for Sean,” she said, adding that it allowed Combs “to watch me with the other person and actually direct us on what we were doing. Eventually it became a job for me, pretty much.”

She explained Combs would “control the whole situation” and that “it was his fantasy,” adding that she felt like she “couldn’t say no” as she “didn’t want to make him upset”.

She told the court that she would ingest drugs at every “freak-off”, that she said were provided by Combs, as it helped her “dissociate” and had a “numbing” effect.

Ventura emphasized that she felt a “responsibility” to make Combs happy.

Combs preferred Ventura to groom herself a specific way – specifically, he wanted her have her nails painted white, her hair combed a certain way and even suggested she get breast implants.

Combs and his team would also periodically take away her laptop or phone. “It depended on how long I was being punished for,” she said.

Over time, she said, “freak-offs” were not something she wanted to do as they made her feel “horrible”, “humiliated” and “worthless”, she said. “It felt like all I was good for.” She told the court that the “freak-offs” could last two to three days sometimes – with no sleep.

“I was an object,” she said. “I was heavily objectified.”

Still, she told the court: “I was in love and wanted to make him happy” and “I didn’t know what ‘no’ could turn into.”

Of how Combs would get during “freak-offs,” Ventura said: “His eyes go black – the version of him I was in love with was no longer there.”

Ventura said that she was expected to take part in the “freak-offs” even while menstruating and that Combs would sometimes direct someone to urinate on her, resulting in bedsheets during these encounters covered in blood and urine. She said she didn’t want that to happen, but “you don’t have a lot of control at that moment”.

“I just felt humiliated, it was disgusting, it was too much,” she said. “I choked, I didn’t want to be doing that, I was in a position I couldn’t easily get out of. I eventually put my hands up and Sean saw and told him to stop. I was choking, too much urine in my mouth. Sean urinated on me at the same time.”

Ventura also testified that Combs would also sometimes record the “freak-offs” on his device. He would also sometimes use her device to record the sexual encounters, she said, but Ventura told the court that she would delete the videos on her phone afterwards.

“I never wanted anyone to see me like that,” she said. “Objectifying me, putting me in compromising, gross positions with strangers.”

She recalled her first meeting with Combs, in 2005, when she was 19.

“I just knew that he was this larger-than-life entrepreneur, musician. Was a fan of the music. I didn’t know too much about him personally,” she said, adding that she went on to sign a 10-album deal with Combs’s record label.

Ventura later released her debut album in 2006, but it would be the only one she ever put out on Combs’s label.

Of how her relationship with Combs developed, Ventura explained how he kissed her on her 21st birthday in Las Vegas and that the incident made her uncomfortable and that she felt “confused”. From there, despite their 17-year age gap, they began to see each other more frequently and “started to develop a comfortable relationship with each other”.

After the pair started dating, which Ventura said “was not public for many years” as Combs was still in a relationship with longtime partner Kim Porter, Ventura described the world Combs lived in as “much different” than her own.

“He had assistants at his beck and call. He could get anything done quickly. He had respect from everyone and he traveled quite a bit,” she said.

Ventura depicted Combs’s tempestuous moods and the resulting violence he would inflict on her if she didn’t act a certain way. She said she never knew if he would show up at her home in Los Angeles happy or yelling, prompting her to have constant “stomach-in-knots” moments.

“Make the wrong face and the next thing I knew I would get hit in the face,” she said. “He would say: ‘Watch your mouth.’”

Over time, she said, she began to experience his “abusive side” and his “controlling side” adding that his mood would vary day to day, which affected her “greatly”.

Ventura recalled that Combs had guns in safes in his multiple homes, which alarmed her. She cited one particular incident during which Combs made her carry one of the guns, something he did on multiple occasions, which “terrified” her.

That incident involved Combs pursuing his longtime rival Suge Knight: “We were having a freak-off in one of his homes in LA and he said Suge was at Mel’s Diner and we packed up and drove down there,” Ventura said.

“I was screaming and crying: ‘Please don’t do anything stupid.’ I didn’t know what they were going to do.”

Combs, who was arrested last September, faces charges including racketeering conspiracy, sex trafficking and transportation to engage in prostitution. He has pleaded not guilty and denied all allegations.

Daniel Phillip, the second witness called on Monday and a former manager of a “male revue show”, was back on the stand on Tuesday morning to finish his testimony and cross examination.

On Tuesday, Combs’s lawyer Xavier Donaldson asked Phillip if Ventura “was in complete control of everything she did” with Combs.

“I cannot say that,” Phillip said.

Phillip later testified about Ventura’s drug use and noted its infrequency during their encounters. He also revealed that he had bigger feelings for her: “Had she ever given me the chance to date her, I absolutely would have.”

On Monday, a jury of eight men and four women heard opening statements, and testimony from the first two witnesses called to the stand by the government.

Prosecutors allege that Combs ran a “criminal enterprise” through his business empire, aided by associates and employees, that engaged in crimes such as sex trafficking, kidnapping, arson, bribery, enticement to engage in prostitution and obstruction of justice – allegedly dating back to at least 2004.

Combs’s defense attorneys acknowledged that Combs perpetrated domestic violence in the past, but denied any involvement in sex trafficking or a racketeering conspiracy, and portrayed any group sex as consensual, describing it as part of a “swinger’s lifestyle”.

Before court adjourned for the day, prosecutors questioned Ventura about the circumstances surrounding the hotel assault captured in 2016 surveillance video. Ventura said that she, Combs and a male escort had been engaged in a “freak-off” in the hotel room, when at some point, Combs hit her. She then grabbed her things and left the room.

Asked how many times Combs had thrown her to the floor like he is seen doing in the footage in the hotel elevator lobby, Ventura responded: “too many to count”.

Proceedings are scheduled to return Wednesday morning with continued questioning by the prosecution.

In accordance with federal court rules, the trial is not being televised. If convicted, Combs, who has been jailed since his arrest last year, could spend the rest of his life in prison.

• Information and support for anyone affected by rape or sexual abuse issues is available from the following organizations. In the US, Rainn offers support on 800-656-4673. In the UK, Rape Crisis offers support on 0808 500 2222. In Australia, support is available at 1800Respect (1800 737 732). Other international helplines can be found at ibiblio.org/rcip/internl.html