I have cheated in my past and I regret it
Thats good that you're acknowledging past behavior but do they know you cheated on them?
Yes, they know that I've made that mistake before.
You should know that cheating on someone is awful and wrong. That being said, it's good to at least realize that you've done wrong.
I've grown up since then.
There is still plenty of growing to do but you're on the right page! That regret will keep you from making the same mistake again since you know what it feels like when someone gets cheated on.