Yes she did and Helios and Diana knew as well that he offed himself after they both abandoned him
I mean did she told him that he died in FL's place leaving his dead body in there and fl witnessed it?
No, only that he succeeded in offing himself. She left him believing that he succeeded the day they first met when she barged in and stopped his attempt.
╥﹏╥ I see, if only he knows how painful it is to her that day when she saw his body
...I forgot if Hestia ever told Cael how he truly died in the past. I can't seem to remember.