you know what,
let her take care of whatever she needs to take care of,
if she has time to ask you to do something,
she has time to do it herself and if she can't be bothered to do it, don't expect to be the fallback guy for her to do the things she doesn't want to do.

"I'm out tonight, won't be back til who knows when so this will have to wait, thx"

And that's it, if she replies, let it go unanswered, remember if it was important enough for her to mention, she should have taken care of it herself, she's been treating you like $hit lately and she has alot of never asking you for favors on top of that - she doesn't get to have it both ways and it's time she understood that but it won't be with your words, it will be with your actions, words without actions are just words and everyone knows they don't do much.