My Ex Can't C** With Her New BF

My ex, my best friend (they're dating) and one other person and I all live in the same house, and I have great hearing and perception so I've figured out she almost never c*** during s**. She can't use a vibrator or her fingers around him either, cause he doesn't like it, so she rubs her c*** while he's in the bathroom- and I have it on good authority that she's using our videos. She always orgasmed with me.