Don’t regret anything.
History is what it is and it’s necessary to have a few chunks of it float under the bridge before you can begin to write the future.
Regrets are futile and will only leave you with a burgeoning pile of what ifs that you can never address. However, you can use bad events from the past to shape the way you deal with your future.
By turning negativity onto its head and producing something positive, it gives your darkness a purpose. An example of this might be in training to be a counsellor, but for now, just tuck that thought away and ditch those regrets.