What to do when you feel lonely?

Lately I've been feeling so alone. My best friend of 10+ years got a new boyfriend. They are always together and I feel like I just got less importent out of nowhere. Beside that I'm in a friendgroup, but I always feel like I'm not as close to everyone as they are with each other. I see them hangout everyday (Individuals, not the entire group and that im the only one not going). It kinda sucks. Even though I know they love me aswell. Yesterday I asked my friend "Hey do you want to hangout tomorrow?" She answered with "Sorry I got school." And then today I find out that she skipped school to hangout with 2 of her closest friends. She did call me with them, but then didn't ask me to join them. It made me feel very shitty. Especially because a few days ago I let her know about this. I told her, "Hey I miss you. I see that you hangout with everyone everyday and I'm happy for you! However sometimes I wish that I could join aswell. We don't speak very often anymore. So do you wanna hangout soon?" She answered with "Oh I'm so sorry I made you feel that way! Yes for sure we will hangout again! Let's do that soon, okay?" But then she pulled the shit she did today. My other friends have no time lately to hangout. I completely understand, however when they ever need me, I'm always there for them, no matter how busy I am. But when it comes to me, they don't do the same. They don't make time for me and it hurts. When my friends do text me or wanna hangout, it almost always is to talk about someone they have a crush on or something that's been bothering them lately. It never is like, "Hey how are you?" It always is like, "Omg I have tea, can u call? But i can't call too long though, I just need to tell you this." I'm happy they trust me that much, but why don't they ever listen to me? I love being alone, I just hate feeling alone... Does anybody know what to do when you feel alone?

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Update: I feel so pathetic haha. My friend just texted me with, "Hey, wanna hangout tomorrow?" I literally started crying happy tears..
What to do when you feel lonely?
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