Yes, I have lots of words of wisdom, but mainly “you need the assistance of an attorney.” In the information below, you listed a number of issues that need to be addressed, so here I go:
Alimony is never a given. The amount and duration, even with the information you provided, are a matter of negotiation. There is no average, which is really frustrating. If I were your attorney, I would begin to negotiate for alimony without a time limit and see what your spouse was willing to offer, since he should understand your situation.
Funds to assist you with the care of your child with “special needs” should be dealt with in child support, not necessarily in alimony. You may want to include provisions in your separation agreement for the continued care of this child past the age of 18 (or graduation from high school).
Living in a nice home, in a good neighborhood, and being able to care for your children are all reasonable needs. Alimony and child support should secure your future and especially the future of your children so that you are all well taken care of. Remember that you only get one chance to get it right, so get all the help you need. Thanks and best of luck!