It’s been said that the way a relationship starts is the way it continues unless something dramatic happens. You two started as a secret from both sets of parents and had a world of your own. Your wife seems to want to continue that arrangement. She wants a world that just includes you and her. Since she has left her parents behind, she wants you to do the same.
It was an unfortunate way to start your marriage, especially since you weren’t entirely willing. It’s an unfair demand for your wife to make now. From what you say, your parents have always been good to you and they have accepted your marriage. You are correct that at their age, they cannot be expected to behave very differently. They are who they are. In addition, they have already lost one child so the relationship with you and your family is all the more important.
Your wife probably doesn’t realize that her unwillingness to be compassionate and accepting of your parents may well end your marriage. It’s never reasonable to ask someone like yourself to choose between people they love. The partner almost always loses.
I realize counseling services are limited in Brazil, but I do think you should make the effort to find a couples therapist. Your wife needs to learn how to manage visits with your parents. You need to learn ways to reassure her of your love and support her emotionally so she can do it.
Do understand that this is not a situation unique to you. In my practice, I’ve seen many couples with this problem. We are generally able to find ways to get someone like you out of the middle and identify strategies so the partner can tolerate it.
I wish you well.