How to give Closure to the person that I love?

Ok here is the short part of my story.. I cheated on my girlfriend and she found out, I feel bad about everything i did to her. she took me back I really want to be with her and i told her i will be faithful and honest from now. which i have . it been months now. but she keep playing back in her head about everything i did... she ask me how i could do that to her .. i told her that i was selfish and i iked the attention.and i foolish for doin that. but she says she wants more like im not telling her everything when i feel like iam... she said she doesnt have that closure.......i been there for her hand and hand.. after thing i diid im trying to making things better each and every day.. sooo im asking asking what is closure and can i give that to herr... helpp ple...