Not on here, I found a relative and a friend on another forum. The friend was terrified of being a parent which I sort of knew, but she felt she couldn't reach out for help IRL and basically cut all her friends and family off.
After I knew this I just loitered in the background so that I could contact her when I knew she was in need. I've never mentioned the forum to her and she's doing great now, but if I hadn't found it I'd have assumed she just didn't want to be friends with me anymore.
The relative was a different situation entirely and I still haven't (and won't ever) forgive her. Her username wasn't identifiable but her profile displayed her email address which I knew. She struggled to conceive, my DS was a surprise. I understood she found this difficult so ignored that part of things, I felt sad I'd made her so upset though.
However, as time went on she kept posting - comments became just mean really, such as my taste in nursery furniture and baby clothes. There didn't seem much point in the comments, by this point she had her own children, yet she'd bitch about me to her friends on this forum thread. They'd laugh and join in, it was awful.
I've never made it known that I know, maybe I will one day but I don't really see the need.