You’ve written an articulate letter about a sensitive topic. I’m sure that there are many people reading it who understand. Sadly, you’re not alone in feeling so alone. Issues of sexuality and family acceptance are often what bring people into therapy.
Once you’ve established that you like and trust your new counselor, a simple way for you to introduce the issues is to ask him or her to read your letter. I do think it’s essential that you find some way to do this and do this early. It would be very difficult for a therapist to be effective in treating your depression without understanding such a central issue in your life. We therapists only have whatever people tell us to go on. When information isn’t shared, it’s hard for us to do our best.
Although I could venture some guesses about the basis for your beliefs and feelings about sex, I’d be stretching. Such issues are so individual and so complicated, that a general response often entirely misses the point. You’ve been wise to find a counselor who can really get to know and understand you. I urge you to make the commmitment to be a good partner in the effort.
I wish you well.