I've had that happen to me. get rid of him. obviously he doesn't think the world of you to even want to get other girls attention, even if it is chatting online and not actually meeting.
he should just come out and say he isn't head over heels over you anymore and that he needs other womens attention. but people don't do that cause they want to keep people on the side as backup.
Honestly, some guys aren't meant to get married. Some men are meant to be alone forever hopping from one girl to the next. If you're husband is the type who will internet creep because he needs attention, you should probably just leave him.
Guys who creep on the internet behind their girlfriend/wife's back are pussies. Instead of manning up and telling you there's a problem or saying it's over, he just goes behind your back. Tell your husband that if he's going to be a creep, to at least be a fucking man about it.
It's also selfish. If he needs/wants to talk to other girls he should have had the decency to leave you first. You need to leave him though. If they do it once, they'll do it again. Men don't change, they just lie and say they will.