is it cheating?

Ouroboros.

What goes around, must come around.

The pepetual motion and cascading of lies to cover lies only ever results in bad vibes; and bad experiences.

Be true, and you'll very quickly spot the liars and bullshitters in your wake.

Edit:

Getting caught is arbitrary. Why the hell does that matter? What that means is that you were really, really shit at cheating and the cause/effect was you got found out.

What you do, when starting a relationship, is enter a thing called MUTUAL OBLIGATION. If one of you fails to see the obligation to that other person, that contract is void and you leave them.

If you cheat WHICH DOES NOT MEAN INTERCOURSE(Will people read Dictionaries; or have they gone out of fashion?)on that person you mutually agreed to having a relationship with then you're just a shitty human being whom broke a social contract with someone whom trusted them to create one in the first place.