My friend lost very personal client information. She had to inform her Manager and the procedure involved telling her client. Contact your Manager or is there a regulatory body who offer legal advice if you have a query? Either you or your employer should have professional indemnity insurance so it protects you if sued.
As a litigant in person I'd stay schtum or simply inform and apologise. I have had many LIPs who deliberately circulate confidential court docs and nothing has ever happened to them apart from the judge saying they deplore what has happened don't do again etc. I've had LIPs forge bank statements, impersonate a solicitor, fake a court order (all separate cases) and all that happened was judge referred to the CPS and no prosecutions ever brought! And those were criminal offences. don't think anything whatsoever will happen as it was an accident if you want to fess up. Pretty sure everyone up to now has assumed you were a solicitor as did I when I read earlier but didn't reply as you'd already had advice