Can my wife drop me from her insurance because we are separated?

Depends on a number of factors.  Did she have the insurance before she was married? Did she do it already? Have you sought legal separation? Have you sought a temporary injunction to prevent her from dropping you until you sort things out? Consult with a divorce attorney in your state (try www.attorneypages.com) and also review the following, also check COBRA:

 §  170-a. Special action. a. A spouse against whom a decree of divorce
  has been obtained under the provisions of subdivision  five  or  six  of
  section  one hundred seventy of this chapter, where the decree, judgment
  or agreement of separation was obtained or entered into prior to January
  twenty-first, nineteen hundred seventy, may institute an action in which
  there shall be recoverable, in addition to any rights under this or  any
  other  provisions  of  law,  an  amount  equivalent  to the value of any
  economic and property rights of which the spouse was deprived by  virtue
  of  such  decree,  except  where the grounds for the separation judgment
  would have excluded recovery of economic and property rights.
    b. In determining the  value  of  the  economic  and  property  rights
  described  in  subdivision  a  hereof, the plaintiff's interest shall be
  calculated as though the defendant died intestate and as if the death of
  the defendant had immediately antedated the divorce.
    c. If the defendant shall  establish  that  intervening  circumstances
  have  rendered  an  award described in subdivision a hereof inequitable,
  the court may award to the plaintiff such portion of such  economic  and
  property rights as justice may require.
    d.  If  the defendant shall establish that the plaintiff has expressly
  or impliedly waived all or some portion of  the  aforesaid  economic  or
  property  rights,  the  court shall deny recovery of all such rights, or
  deny recovery of the portion of such rights as justice may require.
    e. Actions under this subdivision may be brought:
    (i) Within two years of the enactment of this section, or
    (ii) Within two years  of  the  obtainment  of  the  subject  divorce,
  whichever is later.

    § 50. Property of married woman. Property, real or personal, now owned
  by  a  married  woman,  or hereafter owned by a woman at the time of her
  marriage, or acquired by her as prescribed  in  this  chapter,  and  the
  rents,  issues,  proceeds  and profits thereof, shall continue to be her
  sole and separate property as if she were unmarried, and  shall  not  be
  subject to her husband's control or disposal nor liable for his debts.

  § 234. Title to or occupancy and possession of property. In any action
  for  divorce,  for  a  separation,  for  an  annulment or to declare the
  nullity of a void marriage, the court may (1) determine any question  as
  to  the title to property arising between the parties, and (2) make such
  direction, between the parties, concerning the possession  of  property,
  as  in  the  court's  discretion  justice  requires having regard to the
  circumstances of the case and of the respective parties. Such  direction
  may be made in the final judgment, or by one or more orders from time to
  time  before  or  subsequent to final judgment, or by both such order or
  orders and final judgment. Where the title to real property is affected,
  a copy of such judgment, order or decree, duly certified by the clerk of
  the court wherein said judgement was rendered, shall be recorded in  the
  office  of the recording officer of the county in which such property is
  situated, as provided by section two hundred ninety-seven-b of the  real
  property law.

http://public.leginfo.state.ny.us/menugetf.cgi?COMMONQUERY=LAWS

(See 236 Part B, 8. discusses medical benefits by insurance): 8.  Special  relief  in  matrimonial  actions.   a. In any matrimonial
  action the court may order a party to purchase,  maintain  or  assign  a
  policy  of insurance providing benefits for health and hospital care and
  related services for either spouse or children of the  marriage  not  to
  exceed  such  period of time as such party shall be obligated to provide
  maintenance, child support or make payments of a distributive award. The
  court may also order a party to purchase, maintain or assign a policy of
  accident insurance or insurance on the life of  either  spouse,  and  to
  designate  in  the  case of life insurance, either spouse or children of
  the marriage, or in the case of accident insurance, the  insured  spouse
  as irrevocable beneficiaries during a period of time fixed by the court.
  The   obligation   to  provide  such  insurance  shall  cease  upon  the
  termination of the spouse's duty to provide maintenance,  child  support
  or  a  distributive  award.  A  copy  of  such order shall be served, by
  registered mail, on the home office of the insurer specifying  the  name

  and  mailing address of the spouse or children, provided that failure to  so serve the insurer shall not affect the validity of the order.    b.  In  any  action where the court has ordered temporary maintenance,  maintenance, distributive award or child support, the court  may  direct  that  a  payment  be made directly to the other spouse or a third person  for real and personal property  and  services  furnished  to  the  other  spouse, or for the rental or mortgage amortization or interest payments,  insurances,  taxes,  repairs  or  other  carrying  charges  on  premises  occupied by the other spouse, or for both payments to the  other  spouse  and  to  such  third persons. Such direction may be made notwithstanding  that  the  parties  continue  to  reside   in   the   same   abode   and  notwithstanding  that the court refuses to grant the relief requested by  the other spouse.    c. Any order or judgment made as in this section provided may  combine  any  amount  payable to either spouse under this section with any amount  payable to such spouse as child support or  under  section  two  hundred  forty of this chapter.