She was very good at hiding her feelings during most casual interactions, and was clever and generous and fun to talk to when calm, but had almost a second personality which would come out when she became even slightly stressed which was bitter and entirely self-centered and extremely manipulative. She was at that stage of her life completely incapable of maintaining a close personal relationship, and she was frequently (on a daily basis) under extreme stress about perceived grievous slights from everyone around her that were to an outside observer inconsequential mistakes or misunderstandings, and she was harboring numerous long-term grudges.
It seemed like she knew she had a problem, and during times where she wasn’t stressed out would regret her outbursts and seemed to wish she generally had better emotional control. She seemed generally pretty miserable about it, but maybe I was projecting based on the way her problems made me feel.