I recently discovered through digging into social medias that one of my online friend (long term) is lying about some important aspects of his life. Everything he says is confirmed through his social medias (he doesn't know I found them, it wasn't intentional, since we probably use the same emails on every account we have, his profile was showing as suggested) except for one important thing, he has a wife and 2 kids, when he officially claimed to be single and childless.

We've been friends since a long while, just friends, nothing more, and I am not interested romantically or sexually in him, so me knowing about it wouldn't have changed our relationship and I really care about our friendship. I am suspecting he lied at first when we met because he wouldn't have imagined we kept talking and now it's "too late" to tell the truth.

I don't know what I should do, tell him about it or keep it silent? It really doesn't affect our relationship except for the concept of lying, and maybe he has some specific reason to not want to talk about it. What do I have to do?