(((tree))) I'm sorry you are feeling this way.
But you have many good insights! You know that you think others are off having a good time and purposely without you, but that this is something your mind does that isn't real.
You know also that if you can connect with others at the event for your sons, you will feel better, so you are pushing yourself toward doing that so you can feel better.

I think these are such important things to know about yourself! I think you are applying what you learn in thearpy. But so often that involves doing the opposite of what feels familiar. New paths are formidable until they are somewhat worn from use.

My guess is that the pre-therapy you would have withdrawn instead of pushing yourself toward what you think will help you feel better.

Maybe having both things happen at once (needing people and having your needs challenged by your mother's neediness, compounded by her illness) are creating chaos for you and it's hard to see that your needs are important, and come first. But they do. You have to be the best you to be the person you want to be for others.