Congrats dude! Yup watch your spending and keep a spreadsheet of all your bills. You'll be fine though.
As far as your mom, it sucks and is hard, but you have to do what is best for you. She's your mother, so she should want the best for you too. She paid bills on her own for, what, 18 years? She'll figure it out. You gotta distance yourselves from those toxic, one-sided relationships. I think you'll be much happier on your own.