I didn't see anything that said he cheated. I saw that he and his wife had been separated for some time and then a report that he has been seeing somebody else. That's not called cheating, that's called separated.
No, no its not. Not if you are separated and no longer have expectations of marital fidelity. After my wife filed for divorce and moved out I started dating again. Was over a year and a half before divorce was finalized. Was I "cheating"? No. Cheating is when you are in a monogamous, functioning marriage and go behind your partners back with others.