fuck me, how could i ever say that to her?? i'm so ashamed. how could i give up on her so easily??

i'm the one who promised her i'll always be there for her and that my dream is to marry her and whatever and then less than a year into the relationship i suggest breaking up. 

i'm terrified that she will never look at me the same way ever again. I'm scared that her complete trust in my love is now permanently soured even by a little bit. This feels like a permanent historical event in our story together and feels like such a stain on the relationship i can never erase. i just didn't consider her perspective or what she was going through at all and was selfish as fuck.

she told me she's already forgotten it and understands but what if she's pretending? What if this will just be heavy in her heart for the rest of our lives? If she'll have intrusive thoughts sometimes and remember that i once tried to leave her??

Any advice or personal anecdotes or whatever insight would be greatly appreciated.