According to the way Jesus defines adultery, cyber-sex is definitely adultery (Matthew 5:27-28). But Jesus makes a distinction between adultery of the heart and the actual act of adultery (John 8:4). If you are looking for grounds for divorce, forget it. The Bible doesn't give married believers a way out. So we suggest you get some help in resolving your marital problems. You may also want to get all the computers out of your house.