So it’s not black or white in the sense that since one is remarried and the other just not married at all in the eyes of God
A marriage either is or isn’t. It isn’t, for either of them.
So it’s not black or white… that they go to hell?
No one knows WHO goes to hell. So, I don’t get what your fixation on it is.
We don’t know who goes to hell or who doesn’t because there are many aspects to the state of someone’s soul. Those who go to hell die in a state of mortal sin. We don’t know who is in such a state and who isn’t. And, moreover, confession is always available, and we cannot predict who will and who won’t be in a state of grace at some future date of their death. A lot can happen while still living.
Mortal sin requires grave matter, full knowledge, and free will. We don’t know if those things were present or are present for the individuals in this scenario. We don’t know what they’ve done or not done since that time-- such as work with their pastor, go to confession and undertake continence, pursue a decree of nullity and convalidation, etc.
It isn’t your business. It’s their business.
We don’t go around pronouncing people are going to hell. If we are asked about a situation, we provide charitable guidance and suggestions-- such as “mom and dad, perhaps you ought to make an appointment with Fr. X about having your marriage convalidated”. Not “mom and dad, you are going to hell.”