Hi. I am sorry to hear about your problems and glad you managed to do something about it. Sex-positivity means different things to different people.
I had a look at Song of Believers and they are the opposite of Liberum Sexus. It is wonderful you are willing to expose yourself to the Professor's brand of sex positivity. When you start reading In Search of the Final Freedom, you will discover how his sex-positive philosophy developed into an open polyamory Christian community. Although the four books and 48 chapters so far are mostly fiction, the author writes more or less from experience. Just be aware, your understanding of sex-positive will be challenged, even changed. I believe it is a good thing.
My own understanding of sex is that sex models the erotic but does not exhaust the erotic. "When the very Eros of existence is awakened in you, you are awakening as outrageous love. You become an outrageous lover. You begin to live an erotic life. Sex transforms from the pitiful grasping for fleeting fulfillment that is not working for virtually anyone, to something else entirely. Sex is revealed as the potent prose and poetry of reality itself, incarnate as your body and your desire. Sex is revealed as the love story of all of reality, happening in and as you. Sex is revealed as the source of all wisdom, pointing us toward the erotic and the holy in every dimension of life. It is a virtuous circle. Sex models Eros. You begin to live the erotic life in every dimension of your nonsexual life. As you re-eroticize your life, you are personally transformed. At the same time, regular sex transforms into erotic sex. Ordinary sex becomes outrageous sex." (Gafni, Marc; Kincaid, Kristina. A Return to Eros.)
Not enough people have awakened to outrageous love, but sex can take you there. The Campbells in In Search of the Final Freedom are attempting to get there through their open sex-positive marriage. If you take a look at the Professor's photos (as the one below) you might be shocked by the range of his sex positivity.
I hope your invitation will start a hot discussion. Thank you for sharing.