SIster putting family in crisis how do I support her

My sister was diagnosed with advanced breast cancer in 2006.  Since then her cancer has returned 3 times, spreading to the lung in Sept 08 and most recently to the brain in Feb 09.  Her prognosis is poor.  She moved out of her own house, leaving her husband and 16 year son (her daughter is away at college) and moved in with my elderly parents.  My sister called me to come home (I live in India) to help her, which I did this past August.  I'm also staying with my parents.  Her financial situation for herself and her family was in crisis.  They were 3 months behind in house payments and other bills and things became overwhelming cuz of the high medical bills.  Plus she is now unable to work and is in the process of applying for social security disability.  From August to Jan, I coached her and her husband on their finances, raised some funds to help them, and assisted them to catch up on all their bills.  Now that she has had to quit her job AND add to their monthly bills the cost of COBRA for a family policy ($933 a month), they are again in a bad place until she can draw her disability checks, which may be Oct 09 at the earliest.  My sister has slipped into a major depression, feeling like she is losing control of her life way too fast:  loss of health, loss of job, loss of family, etc. To cope with her depression, she started last week spening money to make herself feel better, buying gifts for her kids and treating them to expensive dinners.  In 7 days she went through nearly $600, which is really needed to pay her health insurance premimums next month (that's for her whole family, not just her).  This has been a pattern in her life, and she doesn't seem to understand how self destructive it is and how it ultimately hurts her kids too. My parents are crying, as they cannot afford to bail her out.  They have gone into debt helping her these last 2-3 years.  I also have done all I can financially.  This week our church gave a gift of $1100 to help.  My sister wanted to take $200-300 for more spending.  I told her I would no longer be able to help her manage her finances if she continued to do this.  She was hurt and angry with me, but didn't really say anything.  She just quit speaking to me and would not stay in the same room with me.  The tension was overwhelming for us and my parents.  I left the next day for a 3-4 day break.  My heart is broken cuz I don't know how to help her with this.  I don't know to help my parents.  I feel so helpless.  Mostly I'm grieveing cuz I feel like I'm losing my sister over money today ... not just from her pending death.

SHould I remain in the States, and be available when she needs me again?  Do I stand by and let her destroy her family financially? Do return to India ?  If I do the latter, will she feel abandonned even though she's angry with me and not speaking to me right now?  This is killing me.  I'm hurting so badly for her.  I don't know what to do any more.