What to do when you’ve done something morally wrong?

You learn from it.

You can apologise and you probably should but don't expect them to accept or forgive your apology, especially considering how long it's been. Apologising at this point would only satisfy yourself and your own guilty conscience. The most important thing is that you grow as a person and that you don't wrong others anymore. Consider what it would be like to be in their shoes.

After watching the stranger on netflix I was about to say cover up the murder and blame it on the person most closed to you but in retrospect probably not helpful, you learn you move on and you become a better person is what you should actually do.

I’ve definitely learned from it and like I said I’m not the same person I was then. We’re still talk/friends, is there is anything I can do for them

ten hail mary's and a lord's prayer

I’m an atheist

The only thing you can do is to live by your new standards. You should also acknowledge what happened and profusely apologise. Don't hide from the truth. Embrace it and and allow yourself to learn from the humility. Don't let your pride shield you from your own flaws; don't shy away from acknowledging it because it might be awkward or embarrassing.

After watching the stranger on netflix I was about to say cover up the murder and blame it on the person most closed to you but in retrospect probably not helpful, you learn you move on and you become a better person is what you should actually do.

Just dont let it happen again?
How bad are we talking. Murdered this persons mother, or just spilled a cocktail on their white shirt?

It hasn’t happened again. 1 being spilling a cocktail and 10 being murdering their parents. I’d say a strong 9 even 10 in my opinion

Oh ****. And they still talk to you?!
I would apologize if its been on your mind. Maybe just bring it up and say that your really sorry and you werent thinking straight?