Here is a concise summary of the story:
* The narrator's sister stayed with the narrator's boyfriend's brother, but this is just a precursor to the main story.
* The narrator meets a guy named Fernando at a party and they start dating. Fernando meets the narrator's family and everything seems fine.
* However, Fernando breaks up with the narrator out of nowhere, blocking all contact.
* The narrator is devastated but eventually recovers.
* A shocking revelation: the narrator discovers that Fernando had left them for their own sister, who had been secretly dating Fernando's brother (Alexis) but then started dating Fernando.
* The narrator confronts their sister and exposes the truth to both Fernando and Alexis, leading to a confrontation between the brothers and the sister.
* The aftermath: the sister doesn't forgive the narrator, and Fernando later tries to win the narrator back, but they refuse to forgive him.
Here are the key facts extracted from the text, each with a number and in short sentences:
1. The narrator's sister stayed with the narrator's boyfriend and his brother.
2. The narrator went to study with friends at a cafeteria before a party.
3. At the cafeteria, they met a friend they hadn't seen in years.
4. The friend invited them to a party at his house (Rafa's party) for the upcoming weekend.
5. The narrator attended the party, got heavily drunk, and doesn't remember how they got home.
6. A friend took care of the narrator that night.
7. The next morning, the narrator woke up with a hangover and received a mysterious message from an unknown number.
8. The message was from someone named Fernando, who the narrator met at the party.
9. The narrator and Fernando started talking daily and became boyfriends.
10. The narrator introduced Fernando to their family, including their sister.
11. Unbeknownst to the narrator, their sister knew Fernando's brother, Alexis.
12. The narrator's sister was in a relationship with Alexis but never introduced him to the family.
13. The narrator, Fernando, the narrator's sister, and Alexis eventually spent time together as a group.
14. Fernando suddenly broke up with the narrator, claiming he fell in love with someone else.
15. Fernando blocked the narrator on all social networks.
16. The narrator was deeply hurt and took a month to recover.
17. The narrator's sister revealed she was the one Fernando left the narrator for.
18. The narrator confronted their sister, who admitted to being with both Fernando and Alexis at some point.
19. Alexis was unaware of the situation with Fernando and the narrator's sister.
20. The narrator told both Fernando and Alexis the truth, leading to a confrontation between the brothers.
21. The confrontation resulted in a fight, and the relationships between all parties involved ended.
22. The narrator's sister no longer speaks to them due to the exposure.
23. Fernando later attempted to reconcile with the narrator but was rejected.