I had a similar experience and it wasn’t until I was older and more well read in the Biblical texts and commentaries that I realized the difference between discerning and judging. It is not my job to “judge”; God handles that. I don’t get to choose who goes to heaven or hell. It is my job as a Christian, though, to “discern” sin vis a vis the Bible and our church’s doctrine, avoid it, and encourage the repentance of those who are sinning, and to allow the same for myself.
I agree that with free will, we must discern, but we should leave the judging of a person’s soul to God.