This.

When I originally read OP's post, I immediately became skeptical because people don't elope and then continue to hide the marriage from their friends. The fact that the OP lied to the husband about the kid just so that he stays with her is going to make that marriage unreconcilable because he will always be worrying what she's lying about and trust is one of the pillars of a strong marriage. It is doable, but at 18 yrs old, it's highly unlikely. Just put yourself in the husband's shoes, he's having this kid, knows it's not his, may not know that he will be responsible because the kid is being born into the marriage which automatically makes him the father which will come with it's own set of consequences if the marriage doesn't work out, e.g. child support payments for a baby that's not his. All of that pressure and burden on him will put him in a really bad place mentally and based on the OP's other posts, it sounds like it already has. As others have mentioned, the best course of action here is to get therapy and counseling. Maybe the marriage can be salvaged, but if not, then yall need to make that decision before it becomes destructive.