I feel similar, Dylan, even-though I don't often feel anger. I just get depressed and anxious, thinking they hate me and such.
What I find help a little is repeating to myself of the times I've been proven wrong, and that people are just too busy to answer sometimes. And at other times, they might have meant to answer but maybe they had to do something urgent and then forgot about it. They could also have just missed the message. Sometimes I try to distract myself or sleep it off. >.<;

Obviously you've tried to do that too, so I hope it will get easier for you.