I recently gave somebody my bank details to somebody who said they will be using my account to transfer money between personal accounts, and that I would get a commission out of each transfer.

Yesterday, I went to close my bank account with HSBC, and while closing my account they asked me questions about the previous transfers (like who did them and why), 

I told them it forgot who it was but it was a transaction between friends. I am worried that they might prosecute me for fraud and not end up closing my account.

What should I do now? I am worried that they might put me to jail for being involved in money laundering? Should I admit what I have been doing?