As a Man of Mercy, I do feel compassionate towards those Catholics who express to me anxiety that our present Holy Father may not be the lawful occupant of the See of S Peter. But I re-reiterate: no Catholic can with a good conscience decide for himself/herself that the See of Rome has become vacant through heresy. The Church, in some formal and corporate way, would need either to depose a heretical pope (thus, S Cajetan; John of S Thomas) or to declare that he had himself through heresy already forfeited the See (thus, S Bellarmine, Turrecremata). DIY is no good. All traditional theologians over the centuries who have considered the question (yes, there's nothing unCatholic in considering the question) are agreed about this. Forget it.
The practical aspects confirm the absurdity of Sedevacantism. Our Lord promised that his Church was indefectible. And the papacy is by Divine Institution a pretty central institution in the Church Militant. But, according to the Sedevacantists, the See of S Peter has been vacant for a very long time. I'm not quite sure for how long, because they disagree among themselves about when the vacancy began. If since the death of Ven Pius XII, 9 October 1958, then the See has been vacant now for more than 57 years! There is nothing remotely like that in Church History. What is the longest that the First See has ever been vacant? All Catholic sources except one would tell you that the record Interregnum came after the death of Clement IV in 1268, when the papacy was vacant for two years, nine months, and two days. (The Archdiocesan Church of Westminster, which curiously regards the Pisan Antipope Alexander V as a lawful pope and the next lawful pope after him as being Martin V, believes in an Interregnum of 7 years, from 1410 to 1417.)
But fifty seven years? Fifty seven years and counting?? You gotta be joking! And who would elect a pope now? There are no cardinals left from the reign of Pius XII; and how could an Ecumenical Council do so, since a Council cannot lawfully be convoked except by ... a Pope!
Francis is Pope and we need to be in Communion with him and that's the end of the matter. You may feel that there are problems in the Church of Today, and you may even be right to feel that (who am I to judge?), but this particular anti-traditional short-cut out of such problems is not an answer.