<human>: Hi /r/relationships, you guys have helped me before so please help me again...
I have been with my (F21) gf (F20) for almost three years.  We went through hell and high water to be where we are today.  We live together, we do everything together, on the outside we are literally the perfect couple.

Except for one little thing.  I cheated on her last week.  For some stupid fucking reason I decided it would be okay. I told her last night.  Of course, she flipped. I was expecting as such, but I really thought we could talk about it and get through it.

Ever since then she has been on a rampage.  She turned into the meanest person I have ever seen. She picked me apart like it was her damn job and that she had never loved me. I know she does still, somewhere deep down.

She didn't break up with me.  She said that every other person on this earth would, but she wasn't going to. She asked me what I would do in her position.  I said I didn't know, that when I had been cheated on before it wasn't even a question, I gave them another chance. But that was back when I was in abusive, awful relationships.

She asked if people worked through things like this. I said yes. She asked how. And I have no fucking idea

Reddit, I reeeaaallly need to save this relationship, for both of our sakes. 
Have any of you ever been in this situation? Could you fix it? Is there any hope for us?

Condense the text into a few key points
<bot>: Cheated on gf, she didn't break up with me, I want to fix it but I have NO idea how.