B - It sounds like your mom has had a long term, serious mental health issue (my mom suffered w/one her entire adulthood so I understand the road you've been down and what you're facing now...). This isn't a communication issue and you have absolutely no obligation to accept the letter, let alone read it. I agree with Knott and Cat---you have to do what's right for you first and foremost. Your well being is the most important thing. Trust your instincts about this.