Hi B,
It sounds as if your boyfriend's mum had an extremely emotionally repressed up-bringing and that life has taught her to expect the worst, so that she doesn't understand the good feelings others around her may feel. As you predict, it does sound to me as if she might benefit from therapy, but that this would be a long and difficult process for her, even if she were to agree to try it in the first place.
I wonder, is her son sufficiently close to her to be able to broach the subject in some way with her? If he were to express concern about her, would she listen to him and perhaps consider the suggestion if it came from him? Would her other children be willing to involved in this also?
You could perhaps obtain some leaflets in regard to counselling from your GP and offer these to her also. I realise she may well just discard them, but it might get her thinking just to see them. It would show that you you are both concerned about her and that might help too. Whoever did broach the subject with her would need to do it very carefully, I think. It sounds, as you say, like the last thing she would want to engage in. However I suspect your own assessment of the situation may be right and that this is a deep-rooted issue she has. It cannot have been healthy to have lost her father in the way that she did and for it simply to have been as if he had not existed in her home after that. Everyone needs to express how they feel about their grief somehow and everyone needs to talk, in my experience. The emotions and thoughts need to come out somehow. Writing them down can help. Is this something you could suggest to her? Some people write a letter to a lost loved one, even though it can't be sent. It still helps to tell them in a letter all the things you would have like to be able to say. I wonder if this is something that could be suggested to her? At least in this way, she would not need to engage with another person and could do this alone. It also might be a useful first step towards perhaps getting counselling.
Does she have a close friend who might be able to go with her if she were to go and see someone? Or perhaps your boyfriend could offer to take her (if you can get her to the point of considering going to a therapist) and wait for her and take her home again.
Does she get out at all? It can help to get out of the house and do something different, like take up a new interest. She might even join a class and maybe make some new friends there. That could take her mind off things and help her take the focus of off all the pain you say she talks about, if only for a while. It could be a start to moving on. It can change your perspective to meet others who have a different outlook on life.
Whatever you decide to do. I think you can only offer options and suggestions. If she does decide to get help the decision will have to be made by her ultimately, as she will not engage in the process unless she is willing to do so and only she can decide that. It may be that she is so stuck in her ways that she has become too blinkered to accept alternative views and suggestions, but it could be that she rehashes all the pain she feels whenever you see her because she is subconsciously wanting and asking for help. Not knowing her, I can not say, but I think all you can do for the moment is to keep gently challenging her ways and her views and offering ideas and ways to move forward to her and express your concern for her and make it clear, if you do suggest therapy, that you are only doing so, out of that concern for her. Also, it might be better and have more impact if that came from her son and her other children if they were willing.
Perhaps this is something your boyfriend could discuss with them. If this lady thought her children were all concerned about her, any expression of this from them all might have a greater impact.
I am sorry not to be able to be of any more help, but cannot think of anything else to suggest. I think it is very good of you to be so concerned about her as to look for help with this situation from others. I hope you find a way to help her between you all. It does sound to me as if she needs it. Other than suggesting the things that occur to me, I think it would help her to know at least that those around her are concerned for her. By showing and expressing that, she may gradually accept that this may be something she may need to consider finding a way to change. People can change. She doesn't have to stay like this, but I think this is something she will have to reach a realisation of herself over time. All the rest of you can do is try to help facilitate this gently and with kindness and love until she is ready to do that.
As for the pain you are yourself experiencing following the loss of your grand-dad, it is clear she will not understand your feelings in regard to this, or may do deep down. but will be unable to express any sympathy. I hope you are getting support with this elsewhere in you life from other sources and if you need any further help with that, this website can be a huge help. We all understand how you are feeling here and will always be around to offer some support and some sympathy.
I wonder if this lady were to take a look at this website if that might help her understand that there are alternative ways to deal with negative feelings and with grief? Just a thought...
Anyway, I wish you luck and success. It is good of you to care enough to seek help on her behalf. Sending you hug in your own loss, B.