The inability to stop obsessing about sex, from watching porn to having intercourse with strangers, has plagued many celebrities, including "The Prince of Darkness" Ozzy Osbourne. The former Black Sabbath singer recently joined other Hollywood "sex addicts" like Tiger Woods and David Duchovny who've blamed their infidelity on a uncontrollable addiction. Osbourne revealed he is undergoing "intense therapy" for his sex addiction, which put his marriage to Sharon Osbourne in jeopardy.

But is this a real disease or an excuse for cheating?

According to a statement released on Wednesday, the rock singer said:

"Over the last six years, I have been dealing with a sex addiction. I'm sorry if Ms Pugh [his mistress] took our sexual relationship out of context. I'd also like to apologise to the other women I have been having sexual relationships with."

A gray area exists in the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) on sex addiction, despite the 12 million people who suffer from it in the U.S., according to the American Association for Marriage and Family Therapy . The term “sexual addiction” first showed up in the DSM-III in 1980, but was removed in the 1994 edition due to lack of research. Now the DSM-V touches upon it, but very lightly, in a section on sexual disorders:

“Research suggests that sexual response is not always a linear, uniform process and that the distinction between certain phases (e.g., desire and arousal) may be artificial.”

Currently, the lack of classification of it being a mental disorder has made many skeptical, and perceive it as an escape hatch for infidelity.

“Nobody knows about this private behavior,” Dr. Fran Walfish, Beverly Hills psychotherapist and author, previously told Medical Daily .

She added: “You cannot tell by looking on the outside who has experienced these early traumas. It can be anyone walking among us.”

Others believe sex addiction is not a real disorder. A 2013 study published in the journal Socioaffective Neuroscience & Psychology found both sex addicts and non-sex addicts tend to react to erotic images with similar levels of brain activity. This raises questions about whether sex addiction might not really exist.

However, this is only one study. Every sex addict will have different addictive behaviors as well as different consequences. Some addicts may spend all of of their time and money on online porn or at strip clubs, while others may have sex with strangers they meet on the Internet, among others.

Treatment for this behavior involves psychotherapy, medications, and self-help groups. A primary goal of this is to help addicts manage urges and reduce their excessive behaviors while maintaining healthy sexual relationships.

Currently, there are 12 million Americans who suffer from sex addiction. If you’re one of the 12 million, you can visit American Association of Sexuality Educators Counselors and Therapists to find a therapist in your area for help or go to Sexual Recovery Institute.