Hi! I believe I can be of help with this issue.
I can imagine how frustrating and hurtful this situation must be for you. You have done everything above board and you've gone certainly farther than the extra mile, yet she has pressed on with her anger and hurtful letters.
And this is actually the key to my answer to you that you need to consider and think about. You are clearly an intelligent and sensitive woman and you're also levelheaded. Therefore I'm going to be open and honest about this situation.
When a spouse, for example, comes home from work and dinner isn't ready on time and gets upset, the other spouse can say, okay, he's upset about dinner. But when he yells for half an hour, the wife knows: something happened. And when he yells again three hours later after dinner's been eaten and forgotten, then she for sure knows: wow, this isn't about dinner at all! Something is wrong here.
Do you see the comparison?
When she first got upset, okay, she's upset. When you apologized so thoroughly and she responded angrily, then that was a warning sign: something is going on with her other than our weekend plans. When she doesn't let go of it but makes it the centerpiece of her relationship with you and your family, then it's clear, isn't it? Something is wrong with her.
We don't know if this is a mental health issue, a relationship issue she's having with her kids that she's taking out, or a personality problem. There is not enough information here.
But my recommendation?
You need to look on Craig's List for another place to live. You have gotten into another person's emotional difficulties and I don't know that it is healthy for you to get further involved. My sense is that it will not be good for you and that you need to exit. I say this from my experience as a psychologist and with your wellbeing in mind. I'm concerned that she's not healthy right now. So, time to move...
Okay, I wish you the very best!
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