She poo-poos DA because she knows she needs it and won't admit it, most likely.
I have a friend who just started going, she's not in debt but she has issues with under-earning much like you, and is trying to grow out of always expecting someone to come along and bail her out. She's finding it quite helpful.
As for whether they're selfish for not helping you - you're a grown woman. Lots of healthy parents would not be ok with continuing to help out a grown child at your age, especially if they haven't seen signs of responsibility. This I think you just have to accept and get yourself into a position where you no longer need their help. Then you can start to slowly pay them back, even if it's just $10 a month to start, it will demonstrate responsibility.
I know budgeting is not your forte, so get a friend to help you. DO THE MATH and figure out exactly how much you need to meet living expenses each month. Start an envelope system and put living expenses into the proper envelopes each month - this will keep you honest, when you only have $10 left in the week's food envelope you eat rice and beans.
Do the Dave Ramsey Baby Steps. I don't agree with his politics but his approach to getting out of debt is exactly what you need. I would only make one modification - as a single parent, you need a bigger emergency stash than the $1,000 he recommends.
Find extra work, sell some articles or babysit for someone on a regular basis to earn a couple hundred extra bucks a month above and beyond your basic living expenses; this will keep you from having to borrow more from your mom.
Go to MrMoneyMustache dot com and get inspired about ways to reduce your expenses.
Keep a change jar as recommended above.
You can do this - but you need to become independent of your parents and your ex. Time for YOU to rescue YOU, no one else.
