Your result
Possible
We are sorry to be answering this question at all. The honest position is that the marriage-based reduction is doubtful here, and that something else may well work better.
The statute cuts the residence requirement to one year for someone who has a Brazilian spouse or partner and is not separated when naturalisation is granted. It is written in the present tense, and whether a surviving spouse still satisfies it is not settled — so it is arguable rather than safe, and we would not want you to rely on it without checking how it is currently being applied.
What is safe is the other ground. If you have a Brazilian child, that gives you the same one-year reduction outright, with none of the uncertainty, and for a widowed parent it is almost always the better application. Your residence permit is a separate matter: one granted for family reunion does not automatically end on a death, but it can be reviewed, so its basis is worth establishing early.
Failing both, the residence you have counts towards ordinary naturalisation at four years, and that route is unaffected.
Tell us whether you have a Brazilian child, when your residence began, and what your permit says, and we will tell you which application to make.