She said: "You had your time, and now I get the wedding. You got to dress up in high school, but I get to dress up for my wedding with him.
"He may have put a corsage on your wrist, but he will be putting the wedding ring on my finger."
Despite her pride at being the one who got to marry the unnamed man, she admitted to experiencing huge jealousy at now sharing the milestones of a teenage romance with him.
She wrote: "It kills me that I couldn't be there for him because I know I would have actually been there wholeheartedly. I would have done it out of love, not as a popularity appearance."
Higgins told the ex girlfriend that she wasn't "sorry" that she didn't get to end up with the man she's marrying, but assured her that she would "find someone too".
The article has now been shared thousands of times on social media by users who mocked Higgins' "scary" attitude towards her fiancé's ex.
One tweeted: "Jesus Christ, don't even have to read the article. The title alone screams 'bunny boiler'."
"He needs to run! RUN FOR HIS LIFE!!!" another posted.
A third said: "This piece is one example of why I sometimes think, in all seriousness, that the minimum age for marriage should be 30."
"She sounds like she's 1 break up away from being a bunny boiler," another agreed.