Im the father figure for my brother and sister and I need help.

I have always been the looked up to big brother and took care of my brother and sister in every way but financially. Our mother passed away and we got separated and my sister takes it especially rough. She will hurt herself, destroy things ($3,000 TV and another TV , etc). And I'm on the verge of breaking down. I've had this pressure ever since i was young and it continues. My brother is very irresponsible and doesn't listen to anyone but me but I have to nag the hell out of him to get him to do simple chores. I want my sister to be happy and not so distressed. For further detail since my mom's passing my sister has been in split custody with my grandfather and her biological father and it's been very hard on her please help me.Edit: My sister is 7, my brother is 16, and I am 18. My brother and I are together living with our uncle. via /r/Parenting http://ift.tt/2dLKrrw