My teacher/mom don't get my depression?

So my French teacher, let's call him Mr. B is also the coach of the guys soccer team, which my brother is on and my mom is the manager of. Anyway, I'm 15 and a sophomore, I've been going through some stuff and been struggling with depression for the last couple of months, one night everything just kind of fell apart, I went to school the next day and was extremely shaken and couldn't focus. That's what it's been like for the past 2 weeks. The other night at the sports awards banquet Mr. B came up and started talking to me and my mom about how the season went and stuff. I don't know how exactly they got on the topic of me, but all I really remember is him saying "Haha, yeah, and she'll act all depressed and stuff during class, better that then distracting the everyone!" And then my mom laughed and agreed with him! I looked at them and then walked away! I feel so betrayed! I haven't told my mom about what I've been going through, and I'm definitely not going to now! I just don't know what to do, I just feel extremely angry and upset and really really confused! please help!