<human>: Holy throwaway-account, Batman!

Okay, here's what I know:
My father-in-law has struggled with- drugs? Alcohol? for at least as long as my husband has known him (I don't know the details, don't really want to, I guess). He recently started going to some kind of unspecified meetings, and has been sober for about three months now. I am really proud of him! I hope he and I can start to get along in the future because of this, but that's material for another post.

In the course of making these life changes, he felt compelled to tell his son that he apparently had a girlfriend before his mom. As I understand it, my husband was born when his mother was very young (this is in part why he lives in another part of the country than his father, and why my knowledge of this is all a literal and figurative game of telephone). This relationship apparently also ended on an accidental pregnancy.

My husband is a ball of all sorts of confusing emotions over this. He's ecstatic, because he's always wanted a brother (he has a ton of step-brothers, but was basically raised like an only-child on weekdays). At the same time, all we know is that Father-in-law is the only person that knows this guy's identity. He has apparently been raised as someone else's son, and by father-in-law's account, is a happy adult with no reason to suspect. My Father-in-law supposedly met him a few times, but without saying anything about it, so it may be a family friend. I can't help but think *someone* else in his life or in my husband's extended family knows something, because my husband's family as insanely strong features (like, same face planted on different people. Christmas dinner with all the cousins was hilarious. At least to me.)

Anyway, all I know for certain is that this guy lives in the same city where my husband was born, and we could probably find out his name if we asked. We don't know for sure if he *is* father-in-law's son, but it seems highly plausible.

Can you provide a brief rundown of the text in within 3 sentences?
<bot>: Husband has a probable secret big brother, and we can dig further and make contact with him...but, well, should we? Pros and Cons? General advice?