Is the SSPX a cult?
Yes.
Fifteen years ago I might have answered differently.
But, today, I say yes.
You need to realize, though, that it isn't YOU that has "changed" between 15 years ago and today. It's the SSPX that has changed.
15 years ago, they might have had a few subtle, under the surface Messianic delusions here and there, but that was far outweighed by all the good they were doing for the Church and for Tradition (but I repeat myself).
There's nothing hypocritical about fervently supporting the SSPX in 2000 but opposing it fiercely in 2016. If I woke up tomorrow in the year 2000 (don't ask me how that would happen) I'd just as quickly go back to supporting it. There was no reason NOT to fervently support the SSPX, and I mean with all one's energy, time, and resources, back in 2000.
That's precisely what I did, and I have nothing to apologize for in that regard. I am honored to have supported a good, holy, work of God -- the work of Archbishop Lefebvre to preserve Tradition -- both in 2000 when I joined an SSPX seminary, and in 2016 as I support the Resistance. The fight is the same in both cases.