So. How do I say this?

MY MUM ALREADY KNEW I AM LESBIAN.

I jokingly came out to my family months ago, when they said that apparently there's a link between homosexuality and being left-handed. I just blurted out "But I'm not left-handed." My mum was just like "Are you trying to tell us something?"

In the car today, she asked me if any of my friends have boyfriends or crushed. Then she asked me if I have any crushes. I said I did, but I got over them. Bear in mind that I go to an all-girls school. She asked who it was. I said it didn't matter. She asked if I went to school with them. I said yes. She said it's not someone in your friendship group, is it? I said it is. She was like was it Lina? I said yes. Then I said I didn't want her to find out this way. She said find out what? I said that I like girls. She said she already knew, because I had apparently told them about six months ago. I thought that they didn't pay attention because they didn't say anything about it. BUT APPARENTLY THEY DID.

I actually kind of feel sick now, but I've got a cello lesson in less than ten minutes. Help me please.