Hello and Good Greetings to you Lorgneg,
Welcome to the forum and welcome being a dharma practitioner.
My suggestion to you is to be honest with her and accept the outcome.
As a Buddhist we should know and understand of the 5 precepts, not lying, is one of the precepts to follow. This is because not telling the truth is the same as lying. Many times we human have perform guilty actions, we chooses not to tell the truth to hide our guilty actions, this is worse than lying. Rather than not telling the truth, why don't we tell the truth and explain our actions, if we have guilty desires, then why don't we eliminate this guilty desires then we won't be afraid to tell the truth. If there is a thought within you, then it is better to tell the truth to her and explain to her why you feel so.
If she rejects you, then you should accept the outcome. If you have not been hungry before and always feeling full, you would not taste the tastiest food on earth, happiness is not for those who refuse to accept or avoid suffering. Only through the acceptance of suffering only that we can understand and feel happiness after the acceptance of suffering.
What you are doing right now is refusing to accept the suffering of the situation given to you, you are in a delima whether to give up on her or not. I may not understand your situation best as you or others, but running away from the truth which is the resulted of your delima will makes you suffer more. Forget about the past that you have broke with her and forget about the future whether you will be with her, these are not important. Focus on the present, what is more important is being truthful rather than hiding it. If you have done noting wrong, then you will have noting to fear of hiding it.
Let me share with you a small story on acceptance of suffering.
Weeks ago, me and my girlfriend went to this cafe to order the a big original waffle. They serves us with plenty of the speciality made sauce which makes the waffle taste great. Yesterday, me and my girlfriend went to the same cafe again ordering the same food, they decided to cut down on the sauce, presenting to us only 1/3 of the orginal amount we received. So we request for more sauce, their response is that to have more sauce, we had to pay an additional 1 dollar. I agree, after topping up the sauce then we received the same amount of sauce (total up) we get as previous time.
Moments later I ask my girlfriend on the sauce, she seems a little bit unjustified that they have cut down so much sauce as compare to last time. I let her know and share with her that in life we have to learn to accept the outcome of many matters such as this, if I will to be so particular and not able to accept the reduction in sauce, I would not have an enjoyable meal.
So be honest with her and accept the outcome as it is, you have to learn to accept the possible outcome of her decision, for everything in life that we have attachment to, we will lose them eventually. Even if she accept you, you will lose her eventually one day (through death or separation).
However, this does not means that we shouldn't possess things or be in a relationship, but through the understanding of this concept then we know that in life things that we possess/attach will be lost eventually, and what is more important is the focus and learning realising happiness within ourselves and focus on cherishing the ones around us.
Whatever her decision will result in the same outcome eventually, you will lose her, it is not important when you will lose her in the future. It is more important that you focus to show her your compassion that you are willing to love her again, and show her kindness that you are willing to take care of her. Even if she does not accept you and she simply wants to be friend with you, it is her choice of to think that being with you will suffer, then you should wish her the best for the future.
In Short, I will offer directly and indirectly
Every benefit and happiness to all beings, my mothers
I will practice the in secret taking upon myself
All their harmful actions and suffering
Taken from Eight Verses of Mind Transformation
Lastly, have a great day ahead and I wish you for the best.