Linda Lovelace has long been considered an untrustworthy source. She has been caught in so many lies and contradictions that even if her claims were 100% true there's no way to verify them.

Some of her co-stars did admit that her husband/agent/pimp Chuck Traynor was abusive and that she was likely suffering physical abuse from him, though to my knowledge no one has said that they witnessed it firsthand (other than hearing them fight in their hotel room). Her claims that she had a gun pointed at her head on the set of Deep Throat have been refuted by cast and crew members alike. All people who were involved at the time have stated that Lovelace was an active and enthusiastic participant in the film. In order to believe Lovelace's claim that she did her scenes in Deep Throat at gunpoint then you would also have to believe that cast and crew all chose to look the other way while her life was threatened. You would then also have to believe that her co-stars then willingly participated in raping her at gunpoint on camera.

Lovelace also denied doing a bestiality film where she had sex with a dog. Once loops of the film were found and it was proven that she had done the film she then claimed that she was coerced. Several people involved with filming that scene have also claimed that she was a willing participant and that they witnessed no threats made to force her to do the movie.

I think it's generally accepted that Linda Lovelace regretted many of the things that she'd done in her career and spent her later life distancing herself from them through claiming that she wasn't a willing participant. It's also generally accepted that she did those things willingly at the time she did them.

If you are interested in this topic I'd highly recommend the book The Other Hollywood, which is an oral history of the porn industry. It includes interviews with everyone from pornstars to producers, directors, and even FBI agents that were investigating the industry. There's a section on Lovelace from some of the people who knew her and they speak directly about her claims that she was forced to do porn. Several describe Lovelace as a pathological liar. All claim that she participated of her own free will.

If you watch Deep Throat for, uhm, research purposes then ask yourself if she looks like she is under duress at any point throughout the movie. Linda Lovelace claimed that anyone watching Deep Throat is watching her get raped at gunpoint. As someone who has watched the movie I submit to you that she does not appear to be in fear for her life or well-being.