This is very common. The same thing happened to my daughter last year. She was very upset, but realized that the situation was making her unhappy, so she left that group and eventually found other friends. Yes, she did spend a few weekends in her own, but she had to get through it. She had to find her people, and she eventually did.
They are not your people. All of these new friend groups are temporary and will shift and change, as they have already started doing. It feels horrible if you are the one being excluded, but realize that it’s temporary. Just keep doing what you have been doing, and I promise you, you will be okay. Try not to take it too personally. It would be another person if it wasn’t you, and are they really the type of people you want to hang out with if they treat others like this? Just get through a day at a time, and take advantge of whatever social opportunities come your way. You may spend time in your room alone on a weekend, but you will get through it. Your people are there and you will find them, but it all takes time.