I used to "cyberstalk" out of curiosity, but I haven't for a long time. Though I can honestly say that I have never "checked up" on my ex-wife and I don't know whether she's alive or dead at this moment. I hope she's well for her own sake, but it's no longer my business. I'm very happy that we didn't have children.
I did do a little bit of searching on some of my older girlfriends and I did locate a lot of them. To my surprise, many of them had moved far away, so I didn't have to worry about running into them anymore. Cyberstalking really paid off in those cases. One woman I couldn't find anywhere, absolutely zero trace, even considering that she might have married and changed her name, which made me wonder whether something had happened to her. I'll likely never know. Sometimes it's just interesting to find out what happened to people you once knew intimately, people who you once kissed, saw naked, and once thought would stay in your life forever but didn't. It's hard to completely break a connection to someone who you once had deep and complicated feelings for, even if they ended up betraying you.
I didn't do any of this to "get them back" or to "get back into their lives." It was mostly out of sheer curiosity and, honestly, some internet searching practice. For me, once a relationship ends it pretty much stays that way, especially when it ends badly. I don't want people who treated me badly back in my life. I'd rather be alone, honestly. But that doesn't mean they don't come up in my head once in a while, triggering a little curiosity demon...