I'm really worried about my MIL who has completely gone off the deep end. I think she is very mentally unstable but am not sure what to do about her as she has cut off all communication with us/won't answer phone/says she's changing locks to her house etc.
Background: she is an only child and has no family except my DH. It's literally just the two of them in the whole world. She lives alone, a few hours away from us and is clearly depressed. She often visits us and we visit her a lot. She literally smothers DH with love. To the point where its really quite weird - goes to extreme lengths to do the smallest thing.
In recent years she's got quite unstable. She's always been prone to black moods, and is a volatile woman, but now the smallest perceived injustice against her will be turned into ammunition against DH and she'll stop speaking to him.
She's been staying with us recently and yesterday went completely off the deep end. The trigger was that DH spoke sharply to her. He said 'oh for god's sake' to her in a mildly aggressive manner. He shouldn't have done it, but it was literally three words over a minor issue.
She has now totally flipped. She shouted and screamed for a couple of hours, cried, told me how she suffers so badly because he's such a terrible son/treats her so badly etc. Then she packed her bags and got the train saying she never wanted to hear from him again and was changing the locks. She is not answering her phone. She says she's disowning him. The worst thing is that she is utterly, utterly irrational. You literally cannot talk to her her or rationalise things with her. She simply won't listen to reason when she's like this.
Although I am biased I can quite honestly say that DH is a good son, he bends over backwards for his mum and rings her almost every day. There is so much pressure on him, with no other relatives to talk to or help.
It is a really difficult situation. I believe she needs to take anti-depression medication as she is seriously mentally unwell. But to even broach this subject with her would be to risk alienating her even further.
Does anyone have any experience of a similar situation or advice?