Jojo, please do not focus on your past sin. As Christians we are not called to dwell on sin but to restore God's world to its former glory by making it a better place. Both of you should first acknowledge two things:
1. If you are going to try to be married, then you want the best marriage possible. That requires love and forgiveness. Hostility has no logical place.
2. If you choose not to be married and nothing can change your mind, then there's still no reason for hostility.
Yes, adultery is biblical grounds for divorce. That's what the old testament says. However the predominant reason it is justification for divorce is because the adulterer would be executed, and that - being the death of the spouse - would nullify the marriage.
In the new testament we are told that marriage ends with the death of the spouse and that God hates divorce. So if we are to follow the law, let's follow it to the letter. If we want forgiveness, then let's forgive.
I encourage both of you to read the book of Hosea if you haven't. Love is not a feeling. Love does not require trust. We don't need to trust someone to show them love. We only need to trust God to protect us in order to let down our own defenses and start loving them. And we should realize that God loves the repentant sinner. God could have told Hosea to execute his adulterous wife, but instead he told him to buy her back. Hosea's act and obedience to God was a symbol of God's love for Israel and, through relation, his love for all sinners.
Love is a duty. Love is a living sacrifice. Love can simply be a service. If the feelings are not there, they will come after love has been practiced. Jesus did not need to FEEL love for the Pharisees. He just needed to say, "Father, forgive them, for they know not what they do" in order to show them love.
Love is simply a conscious effort to do things that work for the good of those you love. And in this regard it is far more lasting and profound than emotion. Make love a ritual or a habit if you have to. There are worse habits to have than acts of loving kindness, and none of them has as profound of results.
And lastly, don't forget communication. Men and women have vastly different perspectives on life and approaches to problems. This is where misunderstandings abound. But both usually mean well, so let's give each other the benefit of the doubt.