Being her first love or at least her foremost is an important honour. If it were in need of a defender, she would hope in you to protect it. And you would take courage and defend, I suppose. It does matter, and it is not a matter of pride, although, pride can be called a virtue. Pride can be a bad thing, according to Luke, it is unclean. But if being proud of something means you love it, loving is a good thing. Don't cut back on love.
If you love her, you love her honour. The honour of knowing her as a wife, having her acceptance, emotions, appearance, kindness...
So if she has given it to someone else, part of the honour, you are understandably offended, and following that, you must forgive her, whether or not she is your ultimate choice of wife. Because Jesus forgives you and you must in turn even forgive the terrorists true?
Forgiving releases you from thinking of them and their ugliest moments. Such thoughts are worth less than nothing to your happiness...
Real forgiveness is not just forgetting about it, letting it go, or understating how bad it is or lessening what what standard you have for false humility...
Jesus creates reconciliation through His painful death and now glorious blood. Just like you can be born again Jesus blood can fill and cover you, that is, be applied to your presence. It helps us move out some forgiveness, cleans our hearts... can yet lead to being born again.
When were you born again? When was she born again? When she is born again, her spirit will be sanctified and separate from the other man and set for special purposes, maybe for you. The history of her body remains faulted. You can give her that she what she genuinely owes you, she cannot repay, and release her from the that debt, and either pursue her or someone else. You are free. If you find forgiving hard, keep trying. We need the ability to be Christian. Receive the laying on of hands.
Also, the anointing breaks the yoke of bondage and after being born again, if you fornicate, Jesus blood makes you clean, sanctified and restores both your honours.
Jesus doesn't want getting even or just letting it go. He wants, restoration. He paid for it. It should not go to waste.
There are Biblical promises of restoration. "See I make all things new."
Love will build you up.
Her seed and yours are a matter of honour, and becoming a father in so, is an hour, right?
If she is your choice to commit to as your significant other, than forgive her for not giving you the whole honour, but also ask Jesus to re-sanctify her and restore her to you. You don't have to stop loving honour, love itself, friendship, esteem, holiness...
And you have to forgive the other guy. For the inappropriate successful advances on a 19 year old woman.
Try to forgive from the heart and mind and will... make a start, but forgetting is not humanly possible but you can well put the ugly, off your mind quite well.
God loves you wants you whole and restored. So your other half if you so choose and succeed, should be restored, re-imbursed with honour and maybe delivered from an unclean spirit.
Jesus offered the woman at the well, living water. I have personally had some. And it refreshes the heart, makes one want to shout praises. It all comes from Jesus. Jesus is the answer Himself.