There is a time and place that we come across people, and band together, when we need it. There are also times, we ourselves need space. A matter of balance.
If you do talk to this younger woman, understand, she has probably been through a lot, and she does not mean to do these things to you (She may want to treat you better), but that she does these things as a reaction to her trauma, and emotions, it is not entirely her fault, most likely, but she did choose the path she took, and it just shows she needs to love herself more.
This is where space is such a valuable ally. Space allows for you to have self discovery, unhindered by other's opinions. Space removes you from stress, whilst, allowing for others to rethink their life, and do reflection. It is good for us all. Sometimes what we do, is we allow our own emotions in the while, to distort our choices, and this can make us walk away, or make us stay, it totally is circumstantial, this does not mean walking away is the wrong choice.
It sounds like, perhaps she is unjustified, and you just want peace from all this. And I feel that this would be a good time to tell her how you feel, and then to take time alone, don't be afraid to walk away for the time being, it is not that you do not care, or you don't want to give an effort, look at all the benefits of this action. It is a manner of wisdom, not lack of compassion. Because you know, that you need to take care of yourself firstly, keep balance, and you also know she needs to reflect in life. Let it be.
As for the old woman, it sounds sad, but I do not have enough information to assess the situation.
I am going to be honest with you, most of my life, no one has been able to give me the whole truth, or answer my every question, I have felt separate, and alone before, but I figured out, that being alone for a particular amount of time, gives me the chance to sort out my thoughts and clear my head, and that alone, in the secret place, with creator, I have been shown answers no man can give.
So have hope! It gets better! that is a choice too, a choice to desire a better outcome...
P.s. When I am alone, I walk, usually among nature.