I've had Protestants tell me straight up I'm going to hell because I'm Catholic. I've run into this a small handful of times. Of course the same sort of folks might say Billy Graham is damned to hell as well for not being the right kind of Baptist.
Individual Protestants and individual Catholics (and individual Orthodox) may go to hell. Being Catholic, by itself, is no guarantee of being saved. Even believing every doctrine is no guarantee of being saved, so he was technically right that Protestants (some of them anyhow) might go to hell. But to the extent that he intended that simply by being Protestant one might go to hell, he is wrong.
There was a firebrand priest associated with Boston College in the 1950's named Fr. Feeney. His thing was that all Protestants were going to hell. The Vatican examined his teaching and ended up excommunicating him for it. Fr. Feeney took the old Patristic saying that 'Extra Ecclesiam nulla salus (There is no salvation outside of the Church)' and applied it that Protestants were damned. But he found himself outside of the Church as well, until he finally repented. Catholic teaching is that while Protestants are lacking some things, one is not damned simply for being Protestant. The glass is at least still half full.
Extra Ecclesiam nulla salus - Wikipedia
Leonard Feeney - Wikipedia
I believe the Catholic Church presents the true faith, or I wouldn't remain a Catholic. At the same time I reserve the term 'heretic' for those who are obstinate in their refusal to believe truths of the faith, not for people who grew up Protestant. You should dismiss this person's unsettling approach and instead concentrate on seeking the truth as best you can, following your Savior wherever He leads. You are not damned for growing up Protestant, and no less an authority than the Holy Office of the Vatican says so. But you do have, as we all do, the responsibility to come closer to our Lord. If we keep that responsibility we will eventually come out in the same place.