Hi there sooooo tired. So sorry that this is weighing heavily on you at the moment. I heard you say what you wanted; and that is to be able to enjoy life and have your own peace. You surely deserve that now.
It sounds like she can take care of her son, but circumstances have changed. I don't know much about the social systems in place where you live, but I would imagine there will be support she can use and it shouldn't be down to you to fill the gap ?
I wonder how it would feel for you to have a conversation with her about how you feel and what you want to happen with her.