Easier said than done. Each situation is different I guess, depending on what you did to betray her trust. Say you cheated, she may always second guess your actions with other women going forward. Say you lied, she may always question what you are really telling her in the back of her mind. Sometimes you can forgive but its a lot harder to forget.
So, so you think you can tell Heaven from Hell,
blue skies from pain.
Can you tell a green field from a cold steel rail?
A smile from a veil?
Do you think you can tell?
And did they get you to trade your heroes for ghosts?
Hot ashes for trees?
Hot air for a cool breeze?
Cold comfort for change?
And did you exchange a walk on part in the war for a lead role in a cage?