So I don't know if this is a BPD thing, or just severe social anxiety. 

Sometimes when I'm either talking to someone and feel dumb or awkward, or if I feel rejected by them, or even if I'm just with people and suddenly feel awkward or out of place... It's like my brain freaks out, and within the span of seconds I'm shutting myself down emotionally, deciding I don't need people and am strong and independent and don't care.