I agree with TheSadGirl. You've explained to her how her disappearing act is impacting you and she is not validating your feelings or respecting your requests for her to act differently. You are not overreacting. This is a real problem. When is the next time you see her in person? You need to sit down face to face and have a candid discussion. You'll either get your answers or you won't but at least you can make a game plan based on her reactions (stay or leave). I'm sorry you're having such a tough time. I hope you get the answers you are looking for. Good luck.