Loss of a soul mate

I have had ADHD for as long as I remember. I am 20 now almost 21, and I could never find the right woman. One day I found her, she was married and very unhappy. I helped her and in doing so fell in love with her. womans advice even called this man whom she was with a maniac. For nine months we have been in love, I wanted to grow old with her, she knew of my adhd and helped me with so much as I helped her too. Two days ago she told me she couldn't stop loving her old partner, that she wants to try again with him, even though her got another woman pregnant 1 week after she left, she said I have done no wrong, its her and she must do this. but I cant help the feeling she is just throwing our relationship away to try again. I am in peices, this was my love, soul mate and best friend. she said she may love me more but she has to go back to him to find out, because she has known him longer and he was her first love. but she don't want me to move on incase its just emotions and she goes down there and realizes she cant live with him, and wants to come back to me. That because she never properly broke up with him, she cant tell if it would have worked out and must find out. and in my adhd mind all I see is him hurting her or them getting intermit, and anger at how she could do this to me. as i type this I am shaking like a leaf. and want to give up on life. she was perfect, she knew how to deal with my adhd and loved me and I loved her like it would never end, and all the time she has been thinking of him, whom I protected her against, unsure how she feels. after getting the last of her things, and watching a movie called rent, some words in it tipped the scale and made her want to try. I could understand I i had done some wrong, but I never did, I cant bare the thought of being without her. I don't know if I should let her do this, go to him, so if it don't work out then she will return to me and be devoted. But if it did work out I would lose the only thing worth living for to me. anyone know what I should do as the adhd part of my brain is going insane