Legal Question in Real Estate Law in Maine

You seem to have 2 issues present in this question. The more academic question is if she can sell YOUR interest in the home, and the answer is "no". She can sell her interest, and I question what her interest would be worth to someone if your interest remains with you. Nevertheless, that is the answer. The reason why that is merely academic is that a forgery cannot pass title, even of her interest. If she did not actually sell her interest, then this third party has nothing. Do you still have posession of the home? The third party would need to bring a legal action to quiet title and obtain a Court determination that the bill of sale allegedly from your wife is valid. Seems unlikely such a suit would be brought once the third party is put on notice that it is a forgery.