I feel like a failure

I feel like such a failure at life. I've failed a math class which I've taken already once so now I'll have to a take it for the third time. I've tried, and tried to study but when I take my tests, anxiety takes over and I can't remember a single thing. I don't know what to tell my parents, who are already extremely disappointed I'm taking this class again. I have no one to talk to about this. I try to be optimistic but how more times must I fail before I pass? I've let myself down so many times and it's hard to seem optimistic anymore.