Should i tell her he cheated with me?

[Sal]

I dated this guy over the summer and discovered he had a long time girlfriend. I called him out on it, he shrugged it off, didn't take any ownership on his shitty behavior and I stopped dating him. This hasn't stopped him from randomly texting me. I have access to his gf via her Facebook page. Should I tell her about his bad ways? I'd wan to know so I'm struggling with this. At the same time I don't want to be the bad guy... I know how girls can flip the switch..

[ZeKE]

I would want to know if that happened to me.

[Lovely]

Tell her.
Be like hey, you're boyfriend is a cheater. When I first met him he said he was single and asked me out and what not. Then later in the relationship i found out he had a long-term girlfriend. So i dumped him and now I'm telling you what had happened. Or something like that...?