Richard Taite — a celebrity addiction and recovery specialist — says it’s a good thing  Whitney Purvis is behind bars, because she’s accused of doing some really bad sh*t … allegedly dealing drugs that killed a man.

As TMZ first reported … Purvis — who starred in the reality show “16 and Pregnant” — was arrested Monday for involuntary manslaughter and drug offenses in connection with the fentanyl death of John Mark Harris in Floyd County, Georgia.

She was slapped with the manslaughter charge for intentionally distributing the drug Tranq — which is a combo of fentanyl — an opioid — and xylazine — a horse tranquilizer. Making matters worse for Purvis, the federal Drug Enforcement Administration is now investigating.

According to Taite … the most shocking part of this story is that Purvis is the alleged drug dealer — instead of being the typical celebrity victim, as in the cases of Matthew Perry, Prince and Michael Jackson.

RT points out that if you’re dealing fentanyl and a person dies, then you need to go to jail forever — no matter how famous the dealer is.

Taite — the founder of celebrity rehab center Cliffside Malibuand current executive chairman of Carrara Treatment Wellness & Spa — also warns that Tranq users can’t even be saved by Narcan, the medicine that immediately reverses the effects of an opioid overdose. RT adds that Tranq is currently considered the worst drug on the street, because users shoot it into open wounds, turning them into zombies.

RT says what’s even worse is having to bury your own child, which Whitney was forced to do after her son, Weston Jr., was found dead in his bed last month. Taite goes on to slam Purvis for allegedly killing Harris with a dose of fentanyl after losing her kid, saying she doesn’t have the right to take the life of someone else’s son.