In Massachusetts, if you inherit money during the course of a marriage it is what the courts consider part of the marital estate, subject to equitable distribution under the factors specified in the divorce statute. It doesn't matter whether you are the executor or not. What matters is the amount of money or property that you, and the marital estate, take from your dad's estate.
This answer is provided for informational purposes only. Actual legal advice can only be provided in an office consultation by an attorney licensed in your jurisdiction, with experience in the area of law in which your concern lies.
Any asset received through inhertance in the course of the marriage is by definition a "marital asset", and is subject to distribution upon divorce. That is not to say that a Judge would not exclude all or part of the asset from the property division. A number of factors are in play here, including the use, if any, of the asset during the marriage, the length of the marriage and the age of the parties. The Judge's exercise of his or her discretion is another important factor.