Honestly, it's not your responsibility to give her "more advanced notification" of things that go on in HER son's life. First off, she clearly should be showing more interest on her own, so she won't need YOU to tell her what to do in order to be an adequate parent.
Second... You're not her personal planner... You're not her secretary... and you can't be held responsible that she can't break plans with some old friend in order to witness an accomplishment in her child's life.
Here's the thing about plans... They're just PLANS. They can change at the drop of a hat. Especially when those plans are just to go hang out with an old buddy or whatever this is that's so pressing that she can't postpone it.
In your efforts to not feel overwhelmed, remember this: You're not responsible for her actions, no matter how much she tries to pin it back on you.
As for abandoning your job... I'm sorry to hear that, and I know that must be very tough... But I have faith that you will be able to refocus your life soon... At least to the point that you can find gainful employment.
I know that's not GAL in the strictest sense, but it may help with the detachment process if you dedicate an hour or two a day to doing something job-hunt related. Either way, once you land that next job, you'll automatically start feeling better about yourself and your situation.
