I need some advice not sure what section to post this to but....

Mrs.
Ok so my mom didnt raise me or my 2 brothers. My grandma got full custody with my mom having no visitation rights. My mom has been in and out of our lives since I was 18 months. Shes in and out of relationships even more. She constantly lies and steals. She has had a rough past with being abused and everything. She also does drugs and I dont trust the men she gets with. She recently went back to my brothers dad and he signed his rights away when they were babies so they wont have anything to do with him. Well they have been together for 6 months and he kicked her out. My mom has no place to go bo car wont get a job. And expects me and my brother to help her in these situations. My brother and I are the only ones that have a roof over our heads have a family a multiple kids with out significant others. We pay our bills dont do drugs and do whats right. My other brother just entered rehab and my sister is living with a family that is on all kinds of drugs and just had he second child with he bf. I dont want to be hateful and tell her I cant help her so I havent beeb answering her calls what should I do? Am I wrong for feeling this way?