If my wife and I are getting a divorce after 5 years of marriage and I have no 401k but she does, am I entitled to a portion of it?

In MA, a 401K is considered marital property.  Basically, the portion of the account accrued during the marriage can be divided between the parties,  You must have a Qualified Domestic Relations Order (QDRO) which should be prepared by an attorney to give to the company adminstering the 401K, in order to split the amount of the account.