Here's the relevant sections of the Virginia Code:
"§ 64.1-49. Will must be in writing, etc.; mode of execution; witnesses, and proof of handwriting.
No will shall be valid unless it be in writing and signed by the testator, or by some other person in his presence and by his direction, in such manner as to make it manifest that the name is intended as a signature; and moreover, unless it be wholly in the handwriting of the testator, the signature shall be made or the will acknowledged by him in the presence of at least two competent witnesses, present at the same time; and such witnesses shall subscribe the will in the presence of the testator, but no form of attestation shall be necessary. If the will be wholly in the handwriting of the testator that fact shall be proved by at least two disinterested witnesses."
Now look at this:
§ 64.1-49.1. Writings intended as wills, etc.
"Although a document, or a writing added upon a document, was not executed in compliance with § 64.1-49 the document or writing shall be treated as if it had been executed in compliance with § 64.1-49 if the proponent of the document or writing establishes by clear and convincing evidence that the decedent intended the document or writing to constitute (i) the decedent's will, (ii) a partial or complete revocation of the will, (iii) an addition to or an alteration of the will, or (iv) a partial or complete revival of his formerly revoked will or of a formerly revoked portion of the will."
The long and short of it, her having crossing out your son's name should not invalidate the will; it should only act to remove him as a beneficiary, though you may have to provide extrensic evidence that she had good reason to want to exclude him.
