Her defence team told the court that Antoine and Gargol were drunk and high on marijuana when the argument broke out and that Antoine can not remember killing her friend, although she accepts that she was responsible.
Police arrested Antoine after they found a Facebook selfie that showed her wearing the belt used to strangle her friend.
Gargol was strangled to death and she was found "unresponsive" by the side of a road, said CBC News.
In court, Crown prosecutor Robin Ritter outlined a complicated investigation that took almost two years to complete.
"My client had some very deep-seeded personal issues that she was not dealing with and unfortunately, for whatever reason, we'll never know, they turned into a very tragic situation for all involved", she added.
The prosecutor said Antoine also used social media to lead police on a wild goose chase. Authorities believe that this was Antoine's attempt to throw them off her trail.
A preliminary hearing for the second-degree murder offense was scheduled for next week, but instead, Antoine reached an agreement involving her pleading guilty to the lesser offense of manslaughter.
Antoine said she and Gargol were best friends and were out drinking when they got into an argument, the CBC reported.
She will now serve seven years in prison.
Her legal advisor said her customer had endured a very long time of mishandle in the Saskatchewan mind framework and had gone to police to report manhandle by non-permanent parents a month prior to the killing.
"I will never forgive myself", she said in a statement read in court. She showed up at her friend's house, and hysterically confessed to how she had hurt her friend.
About six hours before the killing, Antoine posted the picture of herself wearing the same belt, according to the outlet. I'm really, really sorry.
Speaking to the press outside court, she said: "I think that the word motive doesn't have much relevance in this particular case".