I dont know how to begin but i think i should say some facts first
Every year i have a new best friend 
I tell that friend everything about me 
But after a year of friendship i begin to feel anxious about our friendship
I start to overthink every word they say and every move they make if they consider me as their bestfriend or If they find me weird or something
So my anxiety starts to eat at me so i try to stop it by ending our friendship 
I start being rude to them until we dont talk anymore.

So this year i have that girl best friend 
We have nothing in cummon and i really dont know how we ended up being best friends
Its been almost a year since our friendship started 
And i told her everything about me
And this is the only person knows how im anxious about friends and how i ruin every friendship i have just to stop being anxious 
I thought this would make her try not to make me feel anxious and maybe try to make me trust her
So the things that are happening now is:
1. We have this group of friends in the university so we always sit with them and whenever we are with them she starts talking to everyone except me 
She is like telling them a story and making eye contact with everyone except me. Its just like im not even there.. i feel like im left behind
I told her twice about this and the second time she said that she is shocked and she never did something like that and she said she will try not to do it next time.
So the next time she tried to talk to me more and make contact with me. But after like a week she went back to the way she was 
So i won't tell her about this anymore but i just dont understand why would she do that if we were best friends. In the otherhand we chat for hours on social media

2. The second thing that annoys me is this:
She doesnt show me how she cares or how she supports me when im feeling bad
Whenever im feeling bad she asks me what is it and i answer nothing (i dont want to talk about it mostly because its my anxiety about her) so instead of trying to comfort me or talk to me she tries to avoid me until im good 
I dont know maybe she is not emotionaly smart

There is alot of other things that i overthink but the point is i just want to stop this
Sometimes i think we have a good friendship but most of the times my anxiety rules me and i dont know what to do
Any advice?