Mom Has Emancipated Our 17 Year Old Daughter, Ramifications

My question involves emancipation laws for the State of: NY

We had a conference this morning in Suffolk County Family court and as a result we agreed to the following

1) An 18% reduction in my child support payments to my exwife who has sole custody of our 14 year old daughter.

2) Our 17 3/4 year old daughter has been living with me for 6 months and refuses contact with her mother due to a host of reasons that I won't get into now.

3) The agreement stipulates that mom and eldest daughter are emancipated and therefore mom has no financial obligation to our daughter going forward.

I have of course questioned my attorney about the potential ramifications but as I sit here absorbing the events of the last hours, days, months and years including my nightmare 3 year divorce that settled in Dec 2009, I have a few more questions that I pose to the knowledgable individuals on this forum.

I understand that when my daughter is 18 in a few short months, custody is a "non issue" for the most part, even though I am obligated to support her through 21 unless something should occur to cause her emancipation from me.

Do I in effect now have "sole custody" at least from a practical point of view? My attorney said something about my ex signing a document giving me decision making abilities (since technically my exwife has sole custody of both daughters) but doesn't the emancipation make that a moot point?

Our original custody stipulation states that we are to "keep each other informed about the health and well being, and whereeabouts of our children (as well as anything else of importance) at all times." There is no communication between my ex and myself which makes this problematic, nor do I feel she "deserves" to know anything about our daughter due to her choosing to relieve herself of any financial obligations to her. Am I placing myself at "legal risk" by not informing her of anything of importance that may occur with our daughter going forward?

Thanks in advance for feedback.