Thanks for the support just2beaccepted.
I have read up a little on on Borderline Personality Disorder and Histrionic Personality Disorder, and there are bits out of each of them that are my MIL all over. I guess I'm not in a position to suggest this to her, or my husband really, as they do not have a close relationship (if one at all). My concern would be though that she would use this to her advantage in some way.
From past experiences if my husband or myself (even one of my family members) had a major health issue and we told her, her very first comment is always 'oh I had/have that... I've been tested for that...'
My husband would not hate me for letting him visit on his own. He has on a few occasions, and pretty much every time he has, she has said things about me to him. He doesn't take it, so it usually ends in an argument and just really upsets him. As I have said he doesn't really have much of a relationship with her, however he remains in contact as he has other brothers and sisters still at home that he just loves to bits and misses heaps. The issues with my husband and his mother go WAY back to childhood. My observation is that things have never been discussed or sorted out. We have tried, my husband poured his heart out, I have never seen him cry so much. But it made no difference at all.
The thing that gets to me is that she gets to pick and choose when she's nice. She gets to send nasty/harsh and totally uncalled for text messages or emails, most of the time completely out of the blue. But we can't react because then it only fuels her. If we don't reply to a text or email (the same day) we cop it. Yet it can take her weeks, if at all, to reply to ours. My husband and I have changed our email address a couple of times and have just told her we are no longer on the net. I try to limit communication through any other means then face to face, so she can't twist or miss read anything we say.
I will talk to my husband about the disorders and see what he thinks. But I am pretty certain there's no way we could get away with mentioning it to her, or her husband. It would just makes things worse.
There hasn't been a major ordeal in a little while, she is very good at acting fake, and pretending nothing has ever happened (when she wants to of course). Me, I struggle with it all the time. I am not a fake person and I hate not being able to be myself. I can't pretend things are all good, when nothing has been talked through, or apologised for. I still feel sick in the gut every time her name is mentioned. But out of respect for my husband and concern for my child, I'm just going to have to go along with whatever mood she chooses to be in. I'm learning real fast, to just shrug things off, and keep telling myself to not let it get to me. I hate it, but I'm not sure what else to do.