Just wanted to say I think you can move on from this, OP.
Your 'friends' sound like they made a cruel and misguided decision which was carried out in the worst possible way. No one can know how unkind it really was because we don't know their justification. Of course you're not wrong to think friends shouldn't cut each other out, as a group, without warning. But it's hard to judge how out-of-step you might have been with the pace of a normal friendship. There's nothing to say for sure that you were ever difficult to be around before their decision to freeze you out.
Sometimes a group turns against one member for no reason and it is horrible. Stigma about mental illness does lead to cruel and prejudiced behaviour sometimes. Sometimes a group of people can talk themselves into a more brutal and less morally accountable position than they would come to as individuals. You shouldn't have to prove this to anyone on the internet. There's also the possibility that it was much harder than you realise for them to feel they were standing between you and total despair, even if you don't perceive that as pressure when you're the one offering support.
I understand how you're haunted by the memory of the looks you were given. They were free to cut you out but that doesn't negate the reasonable expectations of a friend. To rely so much on friendships, only to find them all unexpectedly extinguished in one fell swoop, must have been hellish. You were at least owed an explanation - but these girls were young and probably didn't know how to say anything directly without causing an emotional fiasco. At the time of their 'horrible looks', they were almost certainly shitting themselves apprehensive, having decided to exclude you without anticipating an actual confrontation that evening. What you saw could have been bravado masking other emotions, like an immature boyfriend trying not to bottle his 'we're over' speech. It's no reflection on your worth but you know that, I think. That's why you're so angry.
It might help to consider why they might have been angry, though. People do get angry when they feel their boundaries are being crossed. A friend doesn't always have to provide 'a natter' - not if they're busy, or tired, or feeling like being alone. If you try to force them, they will get angry. Such is life. I don't know how much this could have happened without your realising it at all. When you're anxious, it can be hard to pick up cues. When you were feeling yourself going down and looking for a life raft, could there have been a driven quality to your nattering that reflected your 'I need this now' state of mind? Being absolutely honest, I would feel a bit claustrophobic in that situation, regardless of how lovely you are. And I know that's not fair to you and it's not your fault. But with the best will in the world, I would need to know it wasn't going to happen often, without warning.
Your friends were young and so were you. We have all let people down. Without diminishing how painful it was for you or how badly you were treated, I think this matters so much because of something that has nothing to do with those people. It seems like you can't 'breathe easy' without knowing someone is there to catch you if you're falling. That's not your fault. The appalling lack of psychological help out there is also not your fault. Neither is it your ex-friends' fault. Most 20-somethings are not used to being the last step between 'I'm coping' and 'I'm now in emotional hell'.
If you were in a better place emotionally, you wouldn't need emotional 'catching' and this might be easier to forget because it wouldn't represent the worst thing that could possibly happen to you. So do everything to let this incident go, because it's holding you back. Can you dry the tears of the abandoned little girl who is crying inside and give her a hug? Can you tell her that nicer people do exist, because you're one of them? As many times as it takes? Right now, you seem to be yelling at the universe, needing that sympathetic reassurance back from others. But it has to start with you. Trust your own judgement and make your own peace with this, if you can. I wouldn't trust my inner child to the internet.