OnlyFans model Courtney Tailor should spend the rest of her days behind bars for killing her boyfriend Christian Obumseli … at least that’s how his family feels.

The Obumseli family attorney, Larry Handfield, tells TMZ … Christian’s family is happy Courtney was recently charged with second-degree murder, because a conviction could result in a life sentence.

We’re told the Obumseli family’s faith in the justice system was restored when Courtney was arrested this week and charged in Christian’s death.

Remember … Courtney told cops she fatally stabbed Christian with a knife back in April, but she insisted it was self-defense. It ended up taking about 4 months for her to be criminally charged. All along, Christian’s family believed she killed him in cold blood.

When the family found out Courtney was finally taken into custody, we’re told they were relieved and super emotional … dissolving into tears.

The day after her arrest, footage surfaced that appeared to show Courtney attacking Christian in an elevator just a few months before the fatal incident.

The family’s attorney says he always assured the Obumselis they would get justice, and now they want it served in the form of a life sentence for Courtney.

Courtney’s attorney, Frank Prieto, tells TMZ … “Although the State Attorney, by law, must consider the wishes of the next of kin a criminal case, those wishes often have to give way to more reasonable minds.”