She claims I must pay lifetime alimony for her in VA. We were married for 21 years. Is this true?

There is no automatic spousal support in Virginia.  The court must look at a variety of factors in determining how much support to award and for how long.  There is a general rule of thumb that if you were married for more than 10 years you could be looking at lifeime support, but even that is not automatic and could depend on your abiility to pay and her ability to improve her own earning potential, among other things.  With a 21-year marriage, if you were the primary breadwinner and supporting her throughout the marriage then there is a very good possibility you will be ordered to pay lifetime support, which means until one of you dies or she remarries or lives in a relationship analogous to marriage for more than one year.