Why would my neice be like that with me?doesnt she see what i do?i fixed everything and im the bad guy?

2 years ago my sis got her kids taken away.3 of her kids went to the father n the youngest 1 came w/ me since his dads m.i.a.My sis got enrolled in a rehab n is now emancipated from her program n is now in her own apt and a month frm now will get her son back.at times my sis would spaz out n say she was gonna giv up n i would thrw her son in her face(not physically)n would say if she givs up now its 4eva so she would open her eyes it got crazy but it workd.my neice has seen it hapen b4.i got into an argumnt w/my niece by emailin her y she neva comes 2 visit me but goes 2 otha peoples house all the time n that wat do i gotta do 2 get some attention eventually if i dont im gonna stop tryin.n she writes back saying whatever "aunt" like so called n that im gona make her mom relapse..me?i tok her brother in,i com thrugh always with bdays n holidays cakes presents while my sis was high on meth.ive given my all to these kids losing my whole paycheck 2make ther day and my neice treats me this