... Moshe adds "and we sat in guy opposite beis peor" referring to when klal Yisroel served avodah zara b'rabim, and had forbidden relations...

Here's a short vort from yesterday's "Daf" (Eruvin 41b). Tosfos (first piece in the perek)says that although the Gemara in Moed Katan (17b) implies that sometimes a person's Yetzer Hora overpowers him and he cannot control it, however, a person can be careful not to reach that stage.

As I once posted: Hashem told the "snake" -
הוא ישופך ראש ואתה תשופנו עקב
He (man) will overpower you in the beginning (if he is vigilant when the taivoh is still small), and you will overpower him at the end (if he waits until it gets out of hand).

Hatzlacha

MT