Libra ex strikes again!!!!

Hey everyone I don't know if anyone remembers my post from long ago but anyways I'll make a quick recap because I really need your opinion on what I am about to do, I'm a Sag btw.
So I dated a Libra for 14 months, then he cheated on me with his father's girlfriend daughter. Then, 6 months later I took him back (yes it was stupid but I needed answers) so we hit it off again until I found out that he was still talking to her behind my back and later on discovered that they were indeed dating ever since we broke up. He denied everything about dating her and told me he saw her as a little sister and would never have anything with her, since I caught him in his lie I cut all the communication with him.
Anyways as for now, he constantly keeps sending me messages, adds me on facebook, replies in all the events that I am attending, tells me how disappointed he is that I am being hostile "again" and that "we will see each other again one day xxx". In the past I would be so pissed or will feel bad and that I would reply back to him to put him in his place and that will get us talking again(I'm sure that's his plan all the time) but I am fed up with him showing up in my life and messing me up mentally and emotionally, I just can't continue to ignore this.

What I was planning was this time changing my strategy and instead of ignoring him or replying I want to contact HER
This is what I am planning to send her along with screen shots of the messages:
Hey I think you probably know who I am already. I just want to ask you to ask your boyfriend to stop bothering me. This is what he has sent me so far this month.
I think I have been quiet and I have left you two be happy after what you did. I don't understand his obsession with being friends with me, he doesn't seem to understand that no one in the right mind will like to be friends with someone that cheated on them, if the person who he cheated was you I think it's appropriate to get him to stop bugging me, you can choose to believe me or whatever he tells you but here are the screenshots just in case he tries to denies, which he tends to do, you can choose to believe it or not , why am I doing this? You can hate me forever but I don't want to be involved in anything that has to do with you, I'm doing this because it's not fair that you people keep doing me bad when I haven't done anything bad to you and I it was about time that you stepped into the picture since you started all of this.

Forgot to clarify, I have not contacted him AT ALL or added him as a friend, I have kept ignoring him.
Thank you for reading, please feel free to tell me your thoughts. Would this get a libra away from me? I just can't seem to understand his obsession in keeping me around if he is still with her and knows what he did.

The girlfriend is a Virgo, if any of you virgos can tell me how you would react it will help too.

Honestly, I understand your frustration. It has been my experience that its better to ignore them completely. Anything you do will be perceived as interest. You can block him on facebook. Will this affect your parent in any way? Are you sure you are really over it? I hope it all works out for the best.