Teachers discriminating against LGBTQ students?

So, in my school district, and I think in many, there are rules against discriminating against anyone based on race or sexual orientation. What's really upsetting is that I still see this happening, it's just more subtle.
One of my teachers outed a student. She didn't technically out him though. She knew that their was a rumor about him being gay and so behind his back she told everyone to be nice to him "because he was struggling with issues". I know that you could say she wasn't necessarily being negative about it, but you should have heard the way she said it, the way the class reacted. He actually came out a few years later, and as far as I know, knew nothing about the incident. Not all Christians discriminate against LGBTQ people by any means, but this teacher was particularly obsessed with the bible and always made us sing biblical songs. She made this girl who was an out lesbian and had a really good voice, she made her sing the solo about "washing sins away". I was so upset I felt like crying. Here was this vulnerable young person with talent, and her teacher, the very one who was supposed to be supporting her, was tearing her down simply for being brave enough to be open with people about who she was.
I would like to mention, that I have also had many completely amazing teachers who, without their support, I would not be as happy and comfortable with my orientation as I am today. They were the teachers who played Ted Talks about the children of lesbian couples and about the journey people face to overcome the hate the LGBTQ community faces. The teachers who made me feel suddenly alive and validated and sometimes even like crying in a good way just by saying that they supported marriage equality.
This post has become much longer than I expected it to be, so thank you for bearing with me.
Up until very recently, I've been firmly I the closet, hiding was a skill I perfected. Lately, I've been sort of testing the waters, hinting at my sexuality I subtle ways. In my drama class I did a monologue originally spoken by a lesbian character. My teacher told me it was my best performance, and gave me full points.
Afterwards, I began to notice my grade dropping. I had had an A the whole year up until this point, and had always received 100% in participation, and now, even though I was doing literally nothing differently, I was getting 80% in participation. I ended the semester with just barely lower than an A. I wanted to ask her why she had lowered my grade, but I just couldn't do it.
I feel so STUPID! There are still obvious reasons for keeping your sexuality hidden when possible. Some forms of discrimination are too subtle to fight.