Maine does not have community property law. Maine has what is called a"common law" system. Under that system each spouse in a marriage owns the property that is held in
his or her name. The fact that your stepfather remarried does not by itself automatically give his new wife any rights in the home.
I cannot tell from the information you provided if you have any rights to the home. You state that your mother and stepfather "included [your] name on the deed." Does this mean that your name was actually listed as an owner on the deed to the real estate? If so, you remain an owner after your mother's death. You also state that they named you as heir to the home upon their deaths. In what way did they name you as the heir? Did they each do it in their wills? If your mother named you as heir to the home in her will, did she nevertheless leave her interest in that home outright to her husband? Or did she place restrictions on leaving her home to him? One common restriction is to allow a surviving spouse to live in a house for life, but to have no power to control who inherits the other spouse's share of that house. This is often called a "life estate." Does you mother's will contain this kind of restriction?
If your your name is not on the deed and you are not a legal owner of the property, and your mother left her share in the house outright to her husband, without restriction, that house is now his. If that's the case, he can legally leave the house to whoever he wants to, including his new wife.