Anxiety??

I feel as though I have anxiety and I really want to tell my friends so that they know I'm not just ignoring them or whatever but I'm too scared. My best friend suffers from depression, anxiety and bipolar (all diagnosed) and she recently had an intense falling out with another friend. The person she fell out with claims that she has anxiety but over exaggerates it and my friend is always making fun of her for it because it is undiagnosed. Mine is too but I know there is no other explanation for how I feel. How can I tell her without her doing the same thing?