Having online friends is ok, in fact for someone like me who has avoidant personalty disorder, its almost the only way we can make friends

Sex talk directed at someone online, when engaged in what was understood by both parites in IRL to be a monagamous relationship does constitute cheating, because you are expressing a desire to show intimate affecttion to another even if you do not have the wherwithall to consumate the desire in IRL

just my 2 cents

TJ