I feel jealous

I'm 16, and I've been talking to a girl in my class for the past month. She said she liked me and we were going great but she told me a little over a week ago that she's lost feelings for me and thinks she's a lesbian. Now that hurt me a lot because I thought we were doing perfectly fine. She would flirt and would actually make me feel wanted and I thought there was nothing wrong. She said she still wanted to be friends but we haven't talked since she told me that truth.

I saw her walking in the hallway with her friend on Thursday. She was carrying a bouquet of flowers. I thought "she's just holding them for her friend there's no way she's already got someone." Well on Friday I was proven wrong. She posted on her social medias about her new girlfriend and tagged her in her bio and they seem great together. When I saw that, my heart dropped. I felt replaced, and frankly I still do.

When I was talking to her, that's the furthest I've ever gotten relationship wise. So it hurts to have that basically ripped away and then I see she's with someone new only a week later. She's the only girl that's ever made me feel chosen and wanted.

I tried to talk to my friend about it but he didn't care and it made me feel like ***. He usually cares about the things I tell him and he's usually supportive but this time when I vented to him his only response was "eh that's cool ***." No, it's not cool.

I've already been feeling extremely depressed recently and this isn't helping.

I just wanted to vent somewhere because I feel so bad right now and so lonely. If you got questions about this situation, I don't mind answering them.