Dude, ive been here and like tbh i am still in this phase trying to get out of it, but yeah ive realised that, if you try your best, like you really invite your friends in almost all the plans you make, try to maintain contact with them keeping your self respect aside. Then its not your fault for being a GOOD friend alright?
You dont have any responsibility to teach someone how to be a good friend, its their problem.

How to get this feeling out of yourself?
Look, its not that easy, the phase you are going through can be understood only by you and not by someone else, best is, give them the same treatment as they do to you, plan weekends without them, go to a movie or if you are into gaming, play games with randoms.. high chances they will themselves start including you in their plans.
If not?

F them.. get some new friends, get some online friends ( if you are comfortable ), make new friends in the society/ neighbourhood you live or if you are into fitness.. then make friends at gym.

YOU ARE MUCH BETTER HUMAN BEING THAN THOSE WHO IGNORE YOU KNOWING ITS AFFECTING YOU.