QUOTE:
"...Please pray for us to know how to handle this and also that I can find the right and correct time to share the gospel with them. And break the news that I am Protestant..."
They will know that you are not a RC, because you don't have idols in the house, don't have a rosary, go instead to a home fellowship, etc.
I think in this situation, it is good to begin with witnessing with your life, rather than pointing errors about doctrines.
Aside from their stand as 'cerrado catolico', especially the older ones, the RC has a different point of reference about its doctrines which is not really that easy to tear down as one may recklessly assume unless the one you are witnessing to is ignorant about RC teachings.
Whatever doctrines you may find that are strange are backed up by the RC Tradition which they treat as having equal authority with the bible. They do not believe in sola scriptura.
To them, while the bible is the written truth about christianity, the RC tradition directly came from Christ and His apostles themselves. Only that they were handed down orally, or by other means, faithfully preserved by, and exclusively delegated to the 'one true church', outside of which no one will be saved.
No one shall teach or preach anything apart from what Christ or His apostle have commanded or testified through his church.
How about those dogmas that were written in later dates?
Dogmas or creeds are but doctrines that are formally defined. They are always been there with the church. They are sincere, truthful, and faithfull assesment of the principles and teachings in the scriptures and RC Tradition. They were formalised because somebody or group/s were attempting to pervert, assail, or discredit church teachings.
It was deemed essentially critical to make these official, formal, and or systematic statements for guidance and compliance as to where the church stands against heresies.