In the Gemara in Sanhedrin (26:) Rav Nachman states that even though someone who committed a sin is disqualified from serving as a witness, the aveira of arayos is not as stringent. Tosafos explain that even though the general rule is that a mumar leta'ovin is considered a sinner, the aveira of arayos is different. This aveira has such a big Yetzer Horah, that we cannot condemn someone as easily over a slip in this area.
This may be alluded to in this week's parsha: V'im kol adas yisroel yishgu - if a whole generation of k'lal yisroel may stumble [due to the accessibility of the internet], V'nelam davar mei'einei hakahal - and due to the anonymity (because nobody sees and knows exactly what I am doing online), V'osu achas mikol mitzvos Hashem asher lo sei'asenu - and that will bring to "the one" aveiro which we should not be doing [Hz"l is the WORST aveiro], V'asheimu... V'noda'a hachatos asher chotu alei'ah - even when we realize how low we have fallen, V'hikrivo hakahal - he is still part of the Kahal, and davka through the power of the Kahal (like the group support of the GYE community), he will find his salvation!