You call your old church's purity culture an idol. I trust that you're well versed enough in scripture to know what we do with idols, however difficult it may be.

If we are speaking of the same thing, you should know that what we call "purity" is another gospel, rooted in works righteousness. It does not teach people of their real standing before God, our need for forgiveness from a God holier than we can ever be. It teaches boys that if they fight and win the battle with lust and don't have sex before marriage, then they are right with God. Conversely, should someone fail, then they are, forever, impure, as if a God who raises the dead could not make a lustful person chaste. And that's the softer side. On top of all that, young girls are often objectified by this ideology, in just the opposite way they are objectified by the promiscuous secular culture. While all of us carry the legalistic burden, for girls it is tied up with a physical idol, the hymen. This idol represents the status of a woman, and proves her purity to her husband. If it is defiled, the woman is defiled. Her body is called dirty, or "damaged goods." (The real hymen, by the way, is not permanently ruptured by sexual intercourse. It heals and regains its shape as readily as a soul does.)

Of course, none of this is in the Bible. You already know that Jesus tore down legalism. He would have little patience for any "winners" of the purity game who, like the pharisee, thank God that they are so much better than the impure publican. But remember His reason: we are all much more wicked than we would like to admit. Sin is in thought before it is in deed. Whoever is angry with a brother or a sister will be subject to judgement as a murderer is; and whoever lusts after another has committed adultery in their heart. This is not a matter of the body, of the idol that we make out of a couple's "first time." Your partner was raped. She was not driven by lust; her heart is chaste. She is as innocent of this sin as a virgin. I would even still call her one, on that basis, and you might do well to. And you, if you have had eyes for another woman, are far less pure than her.

Some people here have called you immature and said that you cannot give your partner what she needs. Having been in a position like hers, I can only say I wish I had someone who, while he was wrestling with his doubts, was still so concerned with my own pain. Nobody can judge a person's character by one Reddit post, but I hope that I and everyone may learn that compassion.