Imposter syndrome is pretty common and it sounds like you’ve put in a hell of a lot of work turning your life around, so that’s something you can and should be proud of.
In the meantime though; remember that often it’s not that they actually want to know, they’re just looking for common ground or something to talk about. You can be vague or redirect; “I’m in I.T.” (not a lie) or “I work for a (whatever industry you dev for) company.” (also not a lie) and turn the question back on them. Then ask follow up questions. Most people love to talk about themselves, just give them an excuse.