Lisa, this story reminds me of a clerk who worked in a store where I frequently shopped. She would be helpful, friendly, chatty and upbeat one time; then when I would go back, she would be hostile, suspicious, and rude. She had some kind of mental disorder no doubt.
Your "friend" sounds very needy emotionally. I have such a friend right now, too. For self preservation, you might need to take a break from her. She probably needs professional help. It is not your job to ensure that she is always happy and her feelings don't get hurt. Please don't take that on your self. Tell her she needs to spend more time with other friends as you have family responsibilities and priorities that limit how much time you can spend with her.
Regards,
SandraC