His ex is trying to cause problems?

At this point, your best bet is to cut off all further contact with her. Unless you are summoned to appear before a court, simply ignore and e-mails, texts, phone calls. If they are particularly threatening or nasty, save them in a special folder to be used as evidence if she decides to accuse you of anything. But do not respond in kind, whatever you do. Simply don't respond at all. Unfortunately, yes, you are reaping what you have sown. Guess this is a life lesson that sometimes it's better to let sleeping dogs lie! Hopefully this will just die down, and you can go about your lives. Congrats on the new baby, by the way!