My biggest pet peeve is the whole 'Oh I know exactly how you're feeling.' Do you, do you really? Now I don't mean to sound like a bit of a dick, but when you have had someone stood in front of you saying that when what they really mean is they've just had a bad day or feeling a bit crap for the day it gets a bit frustrating. Maybe I'm just a bit sensitive and I shouldn't take it to heart so much, but it can be hard especially if it's said to you on a particularly bad day.
I don't for one second think just because I have a mental illness anything I go through automatically means it is more significant and upsetting than someone who does not have a mental illness. I know some things I talk about some people may be able to relate, so yes they may know how I'm feeling. But please think before you use that sentence and try to decipher whether you really do know how that person is feeling, don't just say it because you think that's the right thing to say. For many people with a mental illness, including myself, I can at times find it a little insulting. If I have had the confidence to open up to you about something, please listen, you don't even need to try and understand what we're saying we're just happy you're there to listen to our rants and cries!
As I have BPD (Borderline Personality Disorder) I believe you will only ever know how I'm truly feeling if you too have the illness or a similar mental illness. Don't get me wrong, I'm not saying I won't or can't ever relate to someone's emotions in general, but the more severe ones that we/I often struggle to express are the one's I don't think people no matter how close they are too you will be able to relate too and that is perfectly okay. I know I would rather someone say they're not sure how to help than telling me they know how it feels, as I said just listening to us is far more useful.