I know what you've been doing. Stop. Don't even bother to lie to me. I won't tolerate this behavior anymore. When you asked for space I respected your decision to not see each other. While I was a gentleman you were busy lying and deceiving me. Your betrayal has destroyed my trust in you.
I will no longer live like this and have taken the appropriate measures to protect myself and my values. As long as you are committing adultery I have no wish to see you or speak to you.
Enjoy your sick "attraction". Goodbye. <CLICK>
EDIT:
- You do NOT need to tell her how much she has hurt you. - You do not use an accusatory tone of voice with her - Your voice is calm and unemotional as you state the facts (think Gone With The Wind... "Frankly my dear, I don't give a damn") - You have confidence. - You do not whine or complain.
