Brooklyn,
Those who believe there has been no valid Pope since Pius XII are called sedevacantists. I am not a sedevacantist and neither are the SSPX or the people who run the websites of the other two links I sent you. We have a right as Catholics to express our concerns regarding Vatican II and the reforms issued in its name. By doing this we are not saying the gates of Hell have prevailed over the Church. In fact we are doing the opposite by trying to restore the Church by changing the direction we are currently headed in.
The Pope has never declared the SSPX to be heretical. A heresy is a denial of a Catholic dogma. Regardless of the Society’s present canonical status, they have never denied any Catholic dogma, thus there is no question of heresy. Thus one could read the article from the Society website on its own merits and let its arguments stand or fall regardless of who it is that is making them.
The Catholic Apologetics website is Traditional Catholic, but I’m not aware that it is affiliated officially with the Society. I don’t think it is.
The ODAN website is definitely NOT affiliated with the SSPX or any Traditional Catholic organization. That website consists of the testimonies of former members of Opus Dei. Anyone who is considering getting involved with the organization, I think, should at least hear these people out as they were in the organization themselves.
In addition, here is another article written by a modern day Jesuit priest (hardly anti-Vatican II) critical of Opus Dei.
americamagazine.org/content/articles/martin-opusdei.cfm