“Every Catholic must agree with the pope on everything or you are a heretic!”
That simply is not true...the Pope is not infallible...the voting him in is.
“...the Pope is not infallible...the voting him in is.”
Please quote an authoritative source for this, for it is not true. On the other hand, contemplate the following authoritative commentary on the Code of Canon Law:
Finally, one cannot consider as schismatics those who refuse to obey the Roman Pontiff because they would hold his person suspect or, because of widespread rumors, doubtfully elected (as happened after the election of Urban VI) or who would resist him as a civil authority and not as pastor of the Church.
(Franz Xaver Wernz, Ius Canonicum, ed. by Pietro Vidal [Rome: Gregorian University, 1937], vol. 7, p. 398; no translator given; qtd. at http://sedevacantist.com/isitcatholic.html)