I'd be more than happy to assist you. It sounds like a scam. People don't get their email account hacked and need to retain legal counsel because of it. There's a simple fix to this. First change your email account password. Make it something strong, but something you'll remember. Then if your account was actually hacked and someone was sending spam from it, they'd no longer have access to your account (because you changed the password). You can then check your sent items folder and see if you see a bunch of messages there that you didn't send. Either way, DO NOT contact the person who reached out to talking about lawyers. Even if your account was hacked that's absurd. They're clearly trying to take advantage.
My apologies for the delay. Honestly this guy didn't break any laws, he lied to you. But no money exchanged hands. Short of lying to you, he didn't do anything wrong. This is such a basic yet common occurrence I can assure you the authorities will do nothing about it. Your best best is to report him to Google since he's using a Gmail address. They may cancel his account (in which case he'd just open another). Cat and mouse. You can report him here: https://support.google.com/mail/contact/abuse?hl=en
You made a smart move by researching versus paying him money to help you.