NTA.

I understand when times get tough, a family needs to come together and help eachother. That being said, she is asking too much of you, and trying to get you to fill the role of 'husband.' which is obviously wrong for a host of reasons.

She needs to ask her extended family for help, and she needs to go after your father for child support. You should not be working at 16 to help support a family. Working at 16 should be a choice you make for petty cash to spend.

I understand she is having a hard time, and yeah, you probably will need to help out a little more. But she is also using you as a crutch and putting you in a position to 'never leave her.' By making herself and the much younger kids dependant on you, she is making it so you can't 'abandon' her when it comes time for you to go to college.

You are right to set boundries. Don't let anyone make you think differently.