Except as provided in subsection (b) of this section, a will, or any part of it, may not be revoked in any manner. A will may be revoked under the following circumstances: By provision in a subsequent, validly executed will that: Revokes any prior will or part of it either expressly or by necessary implication; or Expressly republishes an earlier will that had been revoked by an intermediate will but is still in existence; By burning, cancelling, tearing, or obliterating the will, by the testator, or by some other person in the testator’s presence and by the testator’s express direction and consent; By subsequent marriage of the testator followed by the birth, adoption, or legitimation of a child by the testator provided the child or the child’s descendant survives the testator; and all wills executed before the marriage shall be revoked; or By an absolute divorce of a testator and the testator’s spouse or the annulment of the marriage, either of which occurs subsequent to the execution of the testator’s will; and all provisions in the will relating to the spouse, and only those provisions, shall be revoked unless otherwise provided in the will or decree.