After the spiritual "high" of Pesach / Kriyas Yam-Suf, getting back to regular life can be rough for an addict. Immediately after kriyas Yam Suf, it says that the Yidden went for three days into the desert and that there was no water for the people to drink. This place was known as "Mara" - meaning "Bitter". Often, after breaking free from life-long habits and desires, one goes through a stage of "withdrawal" where he may feel "dried out". "And G-d showed Moses a branch and he placed it in the water and the water became sweetened". The Aitz or branch, refers to the Tree of Life which represents "G-d and his Torah". As one progresses on his journey to sexual purity, he is able to connect with G-d and the Torah in ways he was never able to before. It is this spiritual connection, this branch from the "Tree of Life", that sweetens the desert waters and replaces the lust and self-gratification that he had become so accustomed to, with the truly life giving waters of spirituality, sobriety, joy and a true freedom.
Without this "branch" from the Tree of Life, the journey in the desert of sobriety remains truly "bitter" and one may end up returning to Egypt - "on the path that I told you that you shall not see again" (Devarim 28:68).
See this page for ideas of how to increase the Torah learning in your life.