Deadbeat Dad Squatting in House For Free, But is on the Deed

[William Coet]

A family member is on the deed to the house with her husband.  They have two young kids together.  He doesn't have a job and has been abusive.  She has a full time job and pays nearly all household expenses including all childcare costs and the home mortgage, taxes, etc.  She has left the house and moved in with a family member along with the two kids because of the abusive behavior.  She is continuing to pay the costs for the house.
In the meantime the deadbeat Dad is statying at the house and refusing to leave unless she pays him for half of the equity in the house.  He is leveraging the fact that he is on the deed.
Any ideas on how to get him out of the house and ideally off of the deed would be appreciated.
Thank you.