Your ex-girlfriend may be giving you a second chance.
She texts you to come back to the gym and that you are missed.
She mentions going to the xmas party alone.
She listens to your side of the story.

She obviously cares about you.

Second chances, even at a friendship level, are extremely rare in our "disposable, instant gratification" world.

But this is a limited time offer. The question you pose of "do i go fast or slow with my mother?" is minor. Your mother is your now, not your future.

Imagine a life where you have boundaries. Where you don't have to hide your mail. Where you don't have to lie about where you went, or who you talked to. Where every opportunity that comes your way, isn't tainted by the thought "how would mom react ?".

Your mom is deeply unhappy. That is not your fault. It is not your job to fix her, either. You can not help someone who doesn't want to be helped. This is no reflection on your value as a human being.

By the way, if she is opening your mail (which is a crime) she is also going through your laundry, your garbage and anything else that is laying around.

As for the idea that getting stuff in an email format will give you privacy, forget it! Next, she will be demanding to search your phone.

Get out while you can , or you will end up in that burial plot.