This is your father's wife of 10 years. Even though it is his pre-marital home, she resides there as his wife and it is her homestead too. Because of the marital relationship, she cannot be "evicted;" and her sons live there with her permission.
If there has been domestic violence against your father, he could seek a domestic violence injunction to have the perpetrators removed from the house. Other than that, I believe he would have to file divorce proceedings and seek exclusive possession of the house. As far as his exposure to alimony is concerned, that is a "fact intensive" issue that would have to be resolved by settlement agreement, or by the court based on the presentation of evidence as to her need, his ability, the equities, etc.
Answered on Nov 20th, 2013 at 6:30 PM