That kind of betrayal is deeply painful. Be kind to yourself, that is the only person you can control. Time will heal you, trust me on this one. You deserve happiness and please know, you will be okay. Grief is how we learn to accept ourselves. Happiness will be your reward. Hang in there, the way you feel will change but it will happen organically. And one last thing, don't let her actions in the past define who you are now.