Matt Gaetz referring to his "son" as his "helper":

[muriel_volestrangler]

30. In 'People', he says he never adopted him

Nestor Galban was 12 and had just arrived from Cuba, where he’d grown up and where his mother had recently died of breast cancer, Gaetz says. Then a state legislator, Gaetz was dating Nestor’s older sister.

And so Nestor moved in with them — “a modern family,” Gaetz says now.

He says that, except for an interruption during Nestor’s junior year after Gaetz and Nestor’s sister broke up, Nestor has basically lived with him since moving from Cuba.
...
Gaetz did not formally adopt Nestor (and he declines to discuss Nestor’s relationship with his biological family now). He re-frames the matter, saying, “Our relationship as a family is defined by our love for each other, not by any paperwork.”
...
Detailing the timeline, Gaetz tells PEOPLE Nestor lived with him for around four years after first arriving in Cuba before going to Miami for his junior year and living with his biological father: “Then he turned 18 it was easier for him to just move back with me.” (Gaetz declines to specify when exactly he and Nestor's older sister broke up.)

Elsewhere in the interview, he describes the sequence of events this way: “There was a time period at the beginning of my service in Congress where, based on his age and other circumstances, it was not tenable for him to live with me."

https://people.com/politics/matt-gaetz-tells-story-boy-he-raised-as-a-son/

It's unclear if the ex-girlfriend formally adopted him (can you formally adopt your own brother?), or just had some form of guardianship, though I'd guess the latter if he didn't stay with her when she and Gaetz broke up.