Let her go...you can't just force someone's hand like that...

I know I cannot. It comes to a reasonable point where I get sad. I even just want to try to get the simplest back

Sounds like you made a big enough mistake that she has no trust in you.

Learn from your mistake and stop doing stupid stuff.

But she's saying she doesn't want to be friends. Maybe she's just too hurt. You have to give her space and respect her wishes. I know it's hard.

I agree pleadong, bargaing, sending friends or families for mediation will only push her further as you don't give her space to see if she even miss having you, not to mention loss of your degnity.

If this girl was your life..you can get her back! Listen, men do mistakes, they mess up. However, if you you still in love with her, and you regret your mistake, there is always a hope to get person back.
She might be mad at you now...give her time to chill down. No mater what you did, you love her and you wants her back.
Wait, and stop contacting her. Try to get back to a conversation mode in a month or so. I am a woman, and I think that we have to know how to forgive if this particular person is not replaceable, he is the one and the only. I would forgive.
As to your mistake..you learnt from it, that's enough. Do not loose hope. If you need an advice..message me.

Hey. I have no clue whether she will ever come back, but one thing is certain: this does not depend on you and it never should depend on you. I also made big mistakes, and I managed to get my girlfriend back. She married me, and we were together 9 years in total. But it just so happens that she never really got over the stupid mistakes I made and she asked me for a divorce last month. She just never felt the same, even though she married me.
At the time she agreed to marry me she thought I was irreplaceable, so she "forgave" me. Now she no longer thinks that I'm so unique, and so she left (maybe with someone else, I have no clue and it does not matter).
The thing is, I never had to really own my mistakes, my unresolved grief and traumas... I just took her and everything in my life for granted, and now I'm paying for it.
Do not walk my path. Own your mistake, and own it on your side, not by having her take you back.
Take a few MONTHS (not days and not weeks) to process the stuff you did, to try to understand why you did it, and to regain your healthy confidence and lose the arrogance or immaturity that made you act out of character. Whether she takes you back or not should have no influence in your search to get over your own flaws.

P.S.: Oh, and stay away from women during that time. You need to sort yourself out. If you just run off to another relationship once you accept your ex is gone for good, you are very unlikely to truly heal and overcome your issues.
Take your time to be with yourself. Work out, learn to draw or play chess or a martial art. Go to the movies on your own... become you! The you that you owe to yourself, not to her or to anybody (well, maybe your kids when you eventually have them =) ).