Is it possible to get into harvard with a 3.7 GPA in freshman year? I did badly because my mom is sick and I didn't take AP classes because I live in Brazil ...

Are you still a freshman? What's your GPA now if you are further into school? This girl I had class with dedicated everything to school and she graduated a year early being number 1 in the school. She's the smartest person I've ever met. She didn't get into Harvard Medical for some reason when her GPA was most likely higher than 7.5 so she now goes to The University of Boston.

Email Harvard's admission board but if that's your weighted GPA it is most likely too low ... Unless it's unweighted on a 4.0 scale and that should be fine

Educated guess: I'd say you still definitely have a good chance but you should look to prove yourself. Like, get good good (high) scores on your SAT / ACT tests. A high score on those should give you better chances