I don't know, first of all....
There is nothing impossible with God. And his mercy is limitless. You are asking if you can be reformed.... well, you should learn about healthy sexuality first.
Theology of the Body - by Pope John Paul, explained by Christopher West is something that has healed my sexuality also.
You should learn about sexuality according to God's holy will, and his will regarding to our sexuality is chastity.
Fill your time with resources of chastity, maybe you can find something to answer your question regarding your struggles.
First of all you need to find God, and forget all the rest. He's the only one that can reform your life.
Try to find Christopher West's talks here. Maybe he will answer your questions. Or see his videos. There are free resources for that
I agree with literary works or quotations, but works by the saints are different. They live the life, not only teach them. And we can imitate that, by reading their works
In catholicism, I think you can only got married once, if you have a third or fourth wife, ... that is living in adultery, and not in conformity with God's holy will.
But to answer your questions, yes, you can be reformed. St Mary Magdalene was a prostitute (and could possibly be an addict, before she was converted)... a prostitute, then a saint. St Augustine and St Margaret of Cortona both had a child outside of marriage and did cohabitated. Yet they were reformed and became saints
God loves us... what he ask is us to love him back.
As a catholic, the sacrament of confession, and forgiveness and love from Jesus is the only thing that can reform our lives, and contrition, and sorrow from our sins.
And pray the rosary, and the divine mercy chaplet. Aside from the sacraments, the thing that can reform your life is prayer. Prayer and the Sacraments are the source of Grace. To reform our lives we need God's Grace, we cannot do it out of our own strength, it is beyond our capabilities. We need God and we need his help and Grace.
If you lean on God, and ask his help, he will help you to reform your life, and start over as a child of God. His forgiveness is something that will heal us and we need to ask his forgiveness because we are sinners.